What Causes Itchy Rashes In The Knee

I have an itchy rash inside of my knees...worse on the left than right knee. My right knee has been itching for several days, with no sign of any rash, bites, etc. Last night, however, I noticed a rash. The rash is raised areas, but not very red. It's actually kind of hard to discern. Also, I've feel like I've been running a low fever for about a week and have had swollen glands. I'm also absolutely exhausted all of the time. I'm 48 and just attributed everything to perimenopause, but the rash seems an odd thing, as I've never had a rash ever, anywhere. I've also been experiencing headaches and muscle aches, which isn't that usual for me. I have a dr's appt. today, but thought I'd ask anyway. Thank you.