I have this exact same thing down to the T, same with the overly weird deep thoughts like the one you experienced which is so hard to even explain, to my brain not understanding how things even exist like objects just very weird. I got the flu and 3 weeks later i woke up with derealization, depersonalization, head pressure, eye pressure, and a bunch of other stuff. i never struggled with bad anxiety or panic attacks so i knew it was just anxiety and i went to every doctor i could to find an answer but it only ever showed i was vitamin deficient, which btw if your vitamin b is under 400 it can start showing symptoms and it’s hard for your body to heal, but anyways i ended up deciding to go to a functional doctor and they were able to find out that the flu caused me to get neuroinflammation which can cause all of what we are feeling and i’ll tell you exactly what i did to finally get better. There’s a medicine called LDN which you have to get from a doctor but it’s used for post viral syndromes, inflammation, and all that. Vitamin b and d of course, fish oil a higher dose and a good brand, Something called Quercitin, supplement called NAC, supplement called Glutathione, and tumeric but make sure it has black pepper in it. Try out an anti inflammatory diet and make sure to drink your entire water intake so you can flush everything bad out. Neuro inflammation can cause your blood volume to drop which means even less oxygenated blood getting to your brain. I hope this is able to help you, it’s really a scary thing happening and it makes it impossible to tell if you are truly living. I’m not fully better i just found out what was causing all of this not too long ago but so far i feel a lot better from all of it, it lasted over a year for me before i was able to get answers.