Good blood flow to the brain is important. A sedentary life or similar rest is counter to this need. But, exercise or effort that causes an increase in symptoms is to be avoided.

A general neuro will not likely be much help. You need to find someone with true experience in concussions, not just any neuro.

Floaters and visual snow are not uncommon. Most floaters are due to a heightened awareness of every little sensation. They were always there, we just did not focus on them. Our properly working brain was able to ignore them. I went through the same observation and was checked out by an ophthalmologist.

The anxiety you are experiencing is one of the most troublesome symptoms of PCS. It can contribute to the sense of derealization. If you research concussions looking for lists of symptoms, you will likely start to self-diagnose symptoms to match the list of common symptoms. Some will be real. Others will be sort of an "I can make my symptoms fit xyz."

The change in how our minds sense and react to stimulation can be very confusing.

btw, The difference you are finding are due to many old school ideas that are still promoted by people who do not stay up on the latest research. Serious rest is only important during the first few days to week or so. After than, moderate stimulation is good as long as it does not cause symptoms to increase.

I suggest you look at next term as a time to take a more moderated course load. You might even talk with your disabilities department and ask for assistance in choosing a lighter load.