For as long as I can remember I would get a heat rash on my knees at random times- sometimes I thought it happened more when I ate salty foods, but I think it is pretty random. I still get this, but the last couple of months I have also gotten painful muscle aches in my legs...to where it is uncomfortable to sit in certain positions and to walk. The first time I had it for 2 full days. Today I started getting it when I got home from a full day of sitting on my butt in in front of my computer at work. After the aching starting on my left upper thigh, it worked its way down to my knee and my knee is hot and slightly swollen. My father has RA and my brother has Gout ....I m scared.