Is swapping meds the right call here? I am second guessing agreeing to it.

30s and male if such info is relevant. I had a regular checkup recently... Primary care physician suggested lowering my dose of Metoprolol from 200MG ER to 100MG ER and switching me from Losartan to Olmesartan.

Been taking those meds for years without issue and my blood pressure has been fine on them. He said he wanted to do it because my heart rate is continually running low (30s-40s), I am not particularly physically fit or active, which is why he said such a heart rate is concerning.

I had no problem agreeing with switching until I got home and looked into the Olmesartan and saw that one of the side effects is potentially severe chronic diarrhea... Due to previous abdominal cancer, the surgeries, radiation, etc., I already suffer permanent diarrhea because I had most of my small intestines removed and only have ~200cm left. And I worried this new med might induce that side effect on my intestines, but it will be masked by the fact that I already suffer chronic diarrhea and I won't know its a problem and it could cause damage to what little intestines I have left. I haven't actually switched to the new meds yet.

If you were in my position, would you ask to switch back?