I think a question only you can answer is will your stress fade away if you quit this job? Usually the answer is no - the mind is a tricky thing - it can find something new to latch onto to cause you feelings of anxiety.
Before you quit, try really hard to enter a different headspace then you're in now and answer this question for yourself.
When I was doing my undergrad, I called my dad extremely distraught as I really believed I was going to get an F in a class for my major. He gave me what I thought at the time was irritating advice, but looking back on it he was right. He told me "Just fail the class if you have too, if you work in X or as a cashier at a grocery store I promise you'll have stress. You've put in a lot of time already, might as well see what happens here".
All this said, if you're literally having physical health issues, you might want to calibrate the above and put your health above everything...