knee pain

Hello,
I ran last night about 5-6km(3-4miles). In my sleep I started feeling pain in my right knee(on the exterior side(lateral part) of my knee more exactly). When I woke the pain was so intense that I couldn't walk with that leg. I had a hot bath and applied Diclofenac.
I left for college and the pain was pretty big, but it started to disappear with time(by time I mean hours). The pain becomes intense again if I go down the stairs.
More info
-I'm 21 years old
-there are no swellings
-din't have any previous injuries to the knee.
-the pain isn't constant, it appears only when walkng
-I think by tomorrow it will be completly gone, should I go to the doctor in any case?

[DrKalraMD]

Hi, this could be due to ligament injury, try elastic bandage, ice compressions, limb elevation during sleep (cushion below leg), anti inflammatory drugs and rest. If no improvement is seen in a week time, do consult doctor for investigations.

For more information visit http://www.drugs.com/cg/knee-sprain.html