TMI number two at the bathroom

Feeling so clogged up at 35 weeks like ill go to the bathroom then a few hours later I’ll go again then it’ll carry on like that. Then the next day I’m literally in pain as if I haven’t been in days! Is baby sitting on my bowel? If I don’t go like 3-4 times a day it’s quite painful. Also I am on iron tablets. Could this be the culprit? Anyone else similar?