It's been 6 days since I developed mild body aches and general ill feeling. Also a pretty persistent right shoulder and arm pain started and is still around. Then 4 days ago I got low-grade fever, usually nocturnal, but now I have it during the day too. It's around 37.8, sometimes 38. I have not travelled outside North America recently. What could be the cause of this? Im hoping it's a self limiting viral illness..but could it be HIV or something serious like that? Just worried because it's lasting a while and the fever came on like 2 days after the other symptoms and is lingering.

Thank you