Pain - iron tablets??

I was told I was anaemic and have to have iron tablets daily for rest of pregnancy. But (and I’m assuming it’s because of the tablets), past few days stomach has been hurting so bad at night, it then takes a while to go toilet (sorry for tmi), but then I do go. Sometimes twice a day (I take tablets in morning). The pain is so bad !!!

Midwife was useless on this. Does anyone know anything that will help me with the pain??