Why do I keep getting diarrhoea?

Just wondering whether anyone has experienced this before. I don't have diarrhoea as in i'm never off the toilet and it's constant buuuut when I feel like I need to go to the toilet I do and then once I've started pooping my stomach starts to hurt and I feel sick and dizzy and sweaty then my normal poop will turn into diarrhoea. It's happened every time for almost 2 weeks now? Should I go to the doctors? idk, it's so random