Day 4 on amoxicillin & I've got bad cramping with urge to use the bathroom

I need some help or advice. I had a tooth infection, im on day 4 of amoxicillin 500mg ( I can usually tolerate it just fine ) but all day today I'm been getting bad stomach cramping which sends me to the bathroom . I've went 6 times today now , started off solid & formed , now it's just soft & mushy ( not completely water ) I suffer from anxiety as well .. I've been taking align pro biotics for about 3 weeks now as well just because I do have a sensitive stomach ( ibs ) but is this normal ? My mind is constantly now thinking I have c diff or something like that .. as I'm writing this I'm getting another cramp . Can I take Pepto bismol??