The most reliable sign of constipation is discomfort with the passage of a bowel movement. Going 3 or more days without a BM can be considered constipation, even though this may cause no pain in some people and even be normal for a few.
Some normal people have hard BMs daily without any pain.
Drinking or eating too many milk products can cause constipation. It's also caused by repeatedly waiting too long to go to the bathroom. After you are better, be sure to stay on a nonconstipating diet so that it doesn't happen again. This is confirmed by finding small amounts of bright red blood on the toilet tissue or the stool surface. Some examples are prunes, figs, dates, raisins, peaches, pears, apricots, beans, peas, cauliflower, broccoli, and cabbage.