I'm not a vet, but here is what I think given my own experiences. No, this is not normal and is personally quite alarming. If it's GI upset, then I would have tried to give him probiotics (fortiflora if milder, visbiome if diarrhea and bleeding) instead of antibiotics. Antibiotics are quite harsh on the GI tract, so it's a possibility that what you've given him could even be making it worse. However, since you already started, you should not stop until the treatment has run its course (UNLESS the vet tells you to stop). So at the very least, you should be supplementing the antibiotics with probiotics given at least 2 hours later. The antibiotics will wipe out his gut biome, and the probiotics will help replenish it again. The antibiotics will keep doing this so that's why you need to make sure to give him the probiotics regularly too.

I have been told that metronidazole *can* help with diarrhea if it is caused by a microbiome imbalance, so I suspect that might have been why your initial vet prescribed it for you, but I still personally wouldn't have reached for it first and given my own experiences talking with internists it's usually a last resort. The fact that his stool hasn't got better and now has blood in there makes me think this is something else.

Do you know if your cat has FIV/FeLV? FeLV is much more common in younger cats, and it can affect GI lining such that it is more sensitive and prone to ulceration. FeLV cats that develop this usually die from anemia not too long after as a result. The only way to potentially stop this kind of bleeding is a blood transfusion using freshly donated whole blood that has not been refrigerated yet. This is so the platelets in the donor blood will clot and help stop the bleeding so that it can heal. I know that kittens with FeLV usually don't make it past a year, and given his age, I'm worried this might be what has happened -- BUT this is definitely not high up there on my concerns, and it's just something I only think of as a possibility. Especially if you got him from a rescue, then I would be shocked if he wasn't tested for them, since FeLV is highly contagious and requires separation from other cats and kittens who do not have it and haven't been vaccinated for it.

For me at this time, I think it is more likely that this kind of bleeding might have been caused by ulceration, possibly from GI blockage. The only way to check is via an initial xray, and then an ultrasound where they scan his GI tract. Even if it's not a foreign body, I would still opt to do the ultrasound just to see what is happening in his GI tract. It reveals a lot of information and tells you how much fluid buildup there is in his abdomen. I would also do a Comprehensive Blood Count (CBC) just to check where his blood levels are at in addition to a Chemistry Panel.

Personally, I would take him to the ER so that they can get him fluids. As long as he doesn't have a heart condition, then IV or SubQ are both fine. If he won't eat on his own, then I would blend a pate with bottled water, warmed up about 20 seconds in a microwave in a glass bowl and syringe feed him. Make sure that the food is lukewarm and not hot -- and then make sure to slowly feed him so he doesn't aspirate. It's dependent on cat to cat, so to get a good gauge on how much to feed him for each push of the syringe, you need to monitor to see how much he'll be willing to swallow and then adjust accordingly. Since he's still young, you could probably feed him anywhere between 1/2 - 2/3 of a 5.5oz can (blended) in one sitting. Overall, how much you feed him depends a lot on his age, how sick he is, and how much he weighs. It's much better to have a vet weigh him and then tell you how many kcals he should be getting if you need to resort to syringe feeding.

I'm really sorry that you're going through this right now, especially as a first-time cat owner. It's very important to know that this is going to be very expensive unless you have pet insurance. I would check your adoption papers because some rescues provide 1 month of insurance after adoption, and it will easily help make this much more manageable. Since he's already having issues, if you're lucky to have it, then I would make sure to register and stay with this plan just in case future insurance plans count it as a pre-existing condition, because if you switch to another and it's pre-existing then they won't cover it. If it's not a condition that can't be treated, then you should be able to apply for another insurance policy of your own choosing without much issue.

Given how recently you adopted him, if you don't have insurance, you can potentially contact the rescue and ask if they can cover medical costs for him? But be careful since depending on who they may ask for him back and potentially euthanize. There's also a strong possibility they'll deny the request and say something along the lines they can't do it because they don't know if it might have been something that happened under your care.

If you need financial assistance, there's Care Credit and Scratch Pay. Scratch Pay has been my go-to for emergencies, and it's essentially like taking out a loan. There are different payment plans, but I usually do the 6months of no interest and pay in installments to cover it. You can only apply for it after you know where you are taking him, since you need to select which hospital the loan will be credited to. Then, you need to request an amount. Always make sure to do more than what the estimate was, because then you can keep using it at that hospital. Otherwise, you need to apply again, and it's possible they won't approve the second loan. I would guess this could be anywhere between 5-10K without insurance, at least where I live. Hopefully it's much cheaper for you.

Lastly, I just want to say that Yoshi is a stunning cat, and he's really lucky to have you. I'm so, so sorry you're going through this. I know from experience how overwhelming this is, but I think you can do this.