Evie - when Liam had his surgery, he was on Antibiotics for about 10 days and pooed constantly... Although I can't be sure it wasn't something else as he was on morphine and panadol too...

In fact, the poo situation took about 3 weeks to come back under control... so good luck!

I woulda freaked too I remember this happening to me when I was about 9. Didn't hurt, but was icky.