Did you have any injury ?
Is the swelling effecting both knees?
On a scale of 1 to 10 how will you rate the pain?
Have you taken any medications?
It only is affecting one knee had xrays at the VA hospital they said nothing was wrong but it has been swollen for six months and said they can't see me till June 2 and I' in pain and have a slight limp from the pain. I fall out of a truck while in Iraq which hurt my back which they tell me there is nothing wrong with also. At least my back isn't swollen
And I am now out of the miltary
Well, you can take Non steroidal anti-inflammatory drugs (NSAIDs) like aspirin, ibuprofen (Advil, Motrin,) and naproxen (Aleve, Naproxen). these are OTC medications, and will reduce pain and swelling.
Also, you can take over-the-counter painkiller product, capsicum for local application. Also Patches containing the analgesic lidocaine are very helpful in this condition.
Also you can see Physical therapist, as they will strengthen the muscles around your knee and help you regain knee stability.
This seems to be case of soft tissue injury . To make a diagnose, you need this test-MRI , it can help identify injuries and damage to soft tissue.
I wish for your good health.