What To Do For The Stiff And Sore Knee Caused By Some Bites?

I was bitten on the knee about a month ago by what I thought was a mosquito, there being a few around. The bite was extremely itchy and surrounded by a defined red circle although no lump. The knee joint is now very stiff and sore. I do have arthritis in the other knee so maybe the two things are unrelated, but still concerned. I was in a tick area but I believe there is no Lyme disease in Australia.