Red rash on penis head?

I ended up getting scabies from a sexual partner late last year and was treated with permethrin cream (two applications) in December. The treatment seemed to work just fine and eliminated the scabies, although the itching persisted for a couple weeks as the doctor said it would.

Most of the itching/rash has gone away completely, but I still have a small red rash/irritation on the head of the penis (top side only, and only on the head). I went back to the dermatologist once in January just to confirm there wasn't a re-infestation and they confirmed I no longer had scabies.

It's been two months since my treatment now, but the rash on the top of my penis still won't go away. Is it possible that this is due to something other than the scabies? Or does it just take longer for the rash to go away on the penis than in other places? Has anyone else experienced a rash like this or had a similar rash after scabies? (Again, it's only on the penis head, and only on the top side. It's just a red rash that is slightly irritated/itchy... no bumps or anything like that.)

I have not had any other sexual partners or sexual contact with anyone since this happened, and have been tested for other STDs (gonorrhea, chlamydia, syphilis, HIV, etc). All came back negative, so I feel like it either has to still be due to the scabies (it just seems weird that it's only on the penis head), or is maybe due to some other skin condition?

Any thoughts on this, or any guys out there who have had similar rashes or experience with a prolonged rash on the penis after scabies?