Okay, now that my post has been approved I see you're talking about online high schools. That may be even trickier. A lot of the online "adult high school" programs either seem to be scams or they don't have the right accreditation that you might need if you decide to pursue future studies.

As for the GED, you can self-study for that by yourself. It doesn't require classes, I don't think (but I don't know). I know of some homeschool programs that actually offer GED review classes, so I don't think it does. There are also some colleges that offer online GED classes. Here's an example. The information you're seeking is really only going to be able to be told to you by someone who works at one of your local colleges, because it seems as if some states offer online programs, whereas others may not. You need to ask them about testing accomodations because all major tests that I'm aware of (ACT, SAT, GED, etc...) offer them to qualified individuals. Panic attacks, if documented by a professional, would likely count, but again, you need to talk to the testing center.

Goodluck!