What causes pain on my knee joint?

Dehydration : Electrolyte abnormalities and dehydration most common. Muscles cramping results. Treat with water, magnesium, more water, salt tablets , and more water. Gatorade/powerade type of electrolyte drinks can be very helpful.

I do not know: Many things can cause pain in the knee joints, from generalized arthritis, to patello-femoral syndrome, overuse, chondromalacia, lymes disease, rheumatoid, etc, etc. The only way to get the most likely cause of your knee pain would be to see the Dr. and get a good History and physical done. Good luck.