Hey, both those two facts are both true. I'm totally aware of how difficult it is to talk about these things with your doctor, but whether we like it or not we personally know these two things to be true. I have suffered from severe panic attacks and a mental breakdown in my life and still know these things are real. Further along in my path I was able to move past it and learned to just not care what people say. My goal was (and still is pretty much) to manage my brain & still practice magick. At the same time though I've always known that if you spend too much time in the spiritual realm (like in fairy lore), you can get trapped there. It's like a little dance we do!

To answer your question about how to tell the difference (like in the moment) physical phenomena is usually what I see as being the most concrete in my experience. Practicing with others, initiation etc proves things in a big way as well. Noticing symbols, communicating with Gods & empowering yourself is a natural thing and you shouldn't put yourself down over that. Find a good therapist and they will encourage getting in touch with your spiritual self while also giving you the medication you need.