What is wrong with my knee?!

What is wrong with my knee?

So, I'm taking this class (strength and running thing) and the first week I was sore---but nothing with the knees. Now, the second week I get up one morning and my right knee feels terrible! Throbbing pain, but then as the day goes on and class does, it feels better. The next day it still hurt and today I go in and it doesn't hurt a bit. Then we run and it does again. Kind of stiff and painful. I get home, but then later today at basketball practice it started to hurt. Throbbing pain again. I touch it and in some areas it hurts. At the end of the tibia, I think. =/ I'm going to ice it, but I was wondering if anyone might have an idea what's wrong?

3 weeks ago
Great... Well, I read that you can rest, ice, take medication, and use bandages or something. I can't quit the class because I'll get kicked out if I miss a certain number of days. I'll just go easy tomorrow. Good thing it's "fun Friday". I'll ice it and try to make an appointment with a doctor. I don't think it's jumpers knee because the class doesn't have...any jumping. It could be...

im not sure if its the same thing but it happened to me a few years ago...
im really active(always playing a sport or swimming or...) but my knee started hurting on the inside. went to a doctor and i had to get mri's and stuff and they came up with jumpers knee. i dont remember the medical term but thats the non-scientific term. well i had to go to physical therapy for like year because surgery couldnt fix it, but therapy didnt really help and it still hurts today