I dont' think that this is going to mess up your disability, go to the doc over your stomache issues, this is showing that you have tried to work and you can't. Keep everything documented. Write it down on a piece of paper with dates, that is considered a legal document. It is obvious that you are trying. But you just can't do it. This does not make you a bad person or anything, know that.
I hope that things work out and that you feel better soon. I can only handle second shift, not first or third.
Keep us posted,
Hugs, Karen