I have been constipated since 3 days now, is that normal? i have also experienced quick, sharp knife-like pain in the anus area a few times over the past 2 weeks. i am worried. what could it be? will it go away on its own?

Can give Dr a call: A college-aged person with constipation wants to be sure there is no other disease causing it. If constipation is just due to slow movement of the food and poop through the gut, then the things to try are vegetables, water, fiber-with-water, prune juice, prunes, polyethylene glycol, Senokot or other senna, milk of magnesia, other laxatives... A doctor can evaluate if symptoms persist or recur.