Painful rash starting at the back of my knee?

I felt itching in a small area about 3 weeks ago. Since then it has grown in size and is like fire! I've been putting coconut oil on it with no relief. It is beginning to trail up and down my leg. Wth is this?! I've seen everything from PUPPPS to herpes to excema! This rash looks nothing like excema but I'm only 17 weeks which would be rare for me to have PUPPPS this early in the game. I am contacting my OB on Monday so I just wanted to know does anyone else connect with this? This is just awful!?