Could be "cutaneous myiasis".. People can become infested if they have contact with infested animals. Less often, the flies lay eggs directly on people
Very well could be some type of arthropod larvae.
Another possibility it that a tapeworm cyst under the skin burst releasing gravid proglottids. Cutaneous cystericus is unusual but not impossible.
Fly strike, google and YouTube this, I have since Calliphora black fly strike in San Antonio Texas l. I have lived up north all my life, and never heard about fly strikes. This devil fly has turned my life into a nightmare. It hit my head hard enough i felt, and of course bc i never felt another movement, it just flew away I thought. NO I washed my hair next day, and it was in my towel. These flies have moved on to humans now, not just horse and cattle! Been to two different Dr.s and won't even come near me!! Hard sticky substance on scalp, Bumps and reddish scabs. Went to ER and was told could not come near me bc of Covid?! After more research, those that have blow fly bite are only dealing w 1 parasite to remove, that is not my case I fear. Throwing everything I can at this, and w no help. Cannot find fly strike even on this site.