Hi welcome to Health care magic..........
has several reasons and depends on age.
You have not mentioned your age. Are there any other symptoms like swelling at the knees , redness
, fever ???
The possible causes -
1) trauma to the knees .
- this is usually in aged individuals.
3) Infection - stahylocoaal or gonococcal
4) Autoimmune - associated with viral illness.
5) Reiters , psoriatic arthritis
are other rarer causes.
U consult a orthopedecian - get a X ray of the knee- it may give a clue to diagnosis.
If there is swelling , then fluid from the knee can be sent for investigation to get a diagnossi.
Treatment depends on the cause.
For pain alleviation can use drugs like Diclofenac
or other NSAIDS.