I've Been Taking 25mg Of Atenolol Twice A Day For

I've been taking 25mg of atenolol twice a day for years with no problems. A year ago I started taking 500mg of metformin 4 times a day. A few months ago the dose was upped to 5 pills a day for a total of 2500mg per day. I take 2 at breakfast, 1 at dinner and 2 at bedtime. At that point I started having a few stomach issues (more sensitive to spicy foods, etc). About a month ago I started taking 5mg of simvastatin at bedtime, and my stomach issues have become much worse. I have to be very careful of what I eat, mostly bland, easy to digest foods, and I have stomach cramps and diarrhea at least twice most days. Is it possible my tummy troubles are from the meds I am taking?