Coming from someone who is always sick,
I'd like to offer a little support. Don't worry about problems that you may not have. Stress affects your body in many MANY different ways. It's not worth stressing over something that you aren't entirely sure of yet. (And even if you do find out for sure, it still doesn't help to stress about it).
Not all teachers are the same, but most of them will understand if you open up to them and be honest about what is really going on.
And finally...
YOU are much more important than your education!!
Best of luck to you dear, you're not alone in this.