Bottom of kneecap hurts really bad after sports a little swollen can't stretch it either been like this for a good 3 months and gets worse what is it?

Knee pain: This may be something called pre-patellar syndrome. This is chronic inflammation and pain of the area around the kneecap. Your doctor can help evaluate and treat this. Since it has been present for three months it does not sound like it is going away on its own.

Will resolve in time: Could be Osgood Schlatters disease, stress where the large tendon going over your kneecap attaches to the bone just below it. It often occurs at puberty, with growth. It may hurt more with running and jumping. It is not serious and will get better over time though it may take several months. You can take ibuprofen, put ice on it, and stretch well.