I have no idea, but I'd see my regular doctor since the ER doc didn't give much info. Good luck!
Erythema relating to Lyme disease is to be ruled out. Possible tick bite.
Considering these symptoms any tick bite should be ruled out. It causes Lyme’s disease which is a long-lasting autoimmune disease in which the immune system attacks normal body tissues as though they were foreign substances. It may cause joint pain. Diagnosed by ANA titres.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.