Im A 25 Year Old Male, Within The Last Few

Im a 25 year old male, within the last few weeks ive had red bumps which started on my back and have spread slighty to my shoulders and even scalp. The itching has subsided but the bumps are still there. A few weeks before this started I received a painful insect bite on my lower back, it was very painful for a few seconds and the gradually subsided, I never found out what it was. Initially there was only a slight red patch and no visible bite mark. I don't know if this is related but I thought I would mention it. I also have a slight tightness in my chest.