Uncontrollable urge to poop after plasma donation

I think I might call it incontinentia, not sure if it is because i can kinda hold it. but man, it's a terrible urge, like the sudden feel of holding a poop for hours and you have to go in that moment. It wasn't diarrhea. Sorry if it's too graphic a description but I want to know if there is a way to fight it. I'm on day 3 post donation and I can control it better but I still feel the terrible urge when it's time.

Any one knows why that might be? And how to prevent it or alleviate it faster?