Hello, I've Been Having Severe Pain In My Body Since

Hello, I've been having severe pain in my body since a couple weeks ago. It started with my right upper thigh and my left hand then my neck and mainly the bottom part of my thumb. Both my knees are bothering me now, and my left knee feels as if its going to pop out of place if i move it a certain way. Also recently started to notice a significant loss of appetite. I'm feeling very week and tired, occasionally light headed throughout the day. Pain is at night and i can't sleep unless i take painkillers and sleep aids. Pain feels like it keeps getting worse and spreading through my body. Please help me with some advice. Thank you.