Is it normal for me to go to the bathroom constantly the night before my colonoscopy?

Yes: The purpose of a colonoscopy is to look at the entire inner lining of the colon. The cleaner the colon is the better the results of the test. Bowel prepping - taking a prescribed laxative to clean out the colon - induces diarrhea. The idea is to get everything out of the colon so your doctor can visulaize as much of the colon as possible. I often recommend desitin (zinc oxide diaper cream) to help protect the skin!

Since: You took a bowel prep to clean out your colon i would expect you to have multiple stools until thoroughly cleaned out.