What Causes Pain And Swelling In Knee While Having Lyme?

Since Fri Dec. 18 I have experienced swelling and pain in my knee. I saw an ortho the tuesday after and tested positive for lyme (also withdrew fluid to look at under a microscope- was turbid). The day I went to the ortho my knee was the best and least swollen it's been, now it is startling huge and getting worse every day. I have a huge protrusion above the knee cap and can no longer identify where the knee cap is. i feel straining in my calf and it feels like the knee cap is being pushed outward and the swelling is beginning to fill underneath. I am completely in the dark about whether or not this is serious and am not sure if i should wait until jan 3 to begin treatment when I have an appointment with a contageous disease specialist. my question is, is this swelling dangerous? could i be damaging myself further? should i go to an emergency room?