26 weeks pregnant ( have diarrhoea and extreme pain in belly area when trying to go.

I've rang the midwife team as it's been like this for (3 days now) the pain gets so bad I'm there crying sweating nearly fainting, anyways they said it sounds normal and if it gets worse to ring back in a few days, I was wondering if anyone else had experienced this? Its only been having recently so I wasn't sure as too why bit surely any sign of pain isnt normal, and I am not being silly I've suffered burst appendix really painful painful periods and cancer so I was used to pain but the pain I've been having actually feels like my painful periods all over again ( I'm not bleeding) it only happens when I go to the loo thank you xxxx