My dad went through similar. He knocked a mole on the top of his head open on a rusty nail. It wouldn't heal for 6 months and kept bleeding, so he finally went to the doc. It had turned cancerous, and the rust from the nail was just making it worse. It took another 6 months for the doctors to do their stuff, when they cut it out.
Now he has a permanent 6" diameter crater in the top of his head, above his eye.
Thankfully it is all done and over, and will not spread.
Good luck with your healing process, and it's a real shame to hear you've had such a rough time with the doctors!