yep, the physical sensations you are experiencing can be anxiety, they are pretty much classic. Still hard to accept when you are feeling the worst of them, I know, but yes, the brain can make us feel all kinds of strange and even painful stuff. Gnashing teeth during the night is common even for folks who are anxious without having it to the degree that it is a disorder, I've had to tell my wife to stop it during when she has had a stressful day, its an unconscious reaction to stress. Bad days are also not uncommon, I am having a rough patch right now, but I will say that when I have had full remission in the past, with the help of medication, the bad days become much less frequent as I became "normal" again. It is a good sign that you are also having good days, it helps to journal so you can prove it to yourself in writing that not every day is bad, because that is what it seems like on a really bad day, but it isn't true, and good days will come again even if it doesn't feel like they will at that moment.