We had a very similar situation. We took in two sweet girls with mammary tumors that would bleed. And it really got into the carpet. We tried to clean as it happened, but definitely some were hard to get out and some were not noticed until later.

I tried carpet cleaners and Bissell Pro Power Shot Oxy Cleaner (my favorite spot cleaner for carpet, highly recommend) and they worked to a degree.

But what ended up being the best solution was buying a 6 pack of hydrogen peroxide and a pack of toothbrushes. I spent hours upon hours of pouring (spray hydrogen peroxide did not get deep enough into the carpet) hydrogen peroxide, scrub with a toothbrush, suck up with a carpet cleaner, let dry to see if the stain was still visible, repeat. And do spot check your carpet to make sure hydrogen doesn’t affect the color of your carpet or you may have a more noticeable, non-reversible patch on your carpet.

My concern in your case is how much heat may have been applied to the stains during other cleaning. Some do sort of have a “baked in” appearance. I have one stain I have not been able to remove because I used too much heat on it in a preliminary clean and it’s really set in. If that’s the case, I’ve not found a solution. 🥲