annie, the doc is best to discuss these things with as mentioned, but when I used mestinon, I kept breaking down the dose in mg until it was tolerable.
I wouldnt take a 30 mg tablet at once, Id break it into 4 pieces and do it over a couple of hours and I didnt have stomach problems anymore.
Sometimes it can be real close, just 10 or 15 mgs more than you can tolerate can cause the problem.