osteoarthritis
"Night pain from knee osteoarthritis - a burning on the medial side - sometimes bothers me at night, particularly if I have been active during the day. If I get up walk around for a few minutes sometimes the pain vanishes. Otherwise  I apply Voltaren gel- about the size of a small grape over the sore place and the pain goes away pretty quickly. I occasionally apply Voltaren ahead of time if I know I'm going to be on my feet a lot. "