They are probably oil glands, and not warts, but truly, the only way to know is to get one biopsied. They don't look like warts, and that 3 doctors have told you that they were oil glands lends itself to being true, but if you can't let it go, see if you can't get one biopsied.
That will probably leave some scarring, so you'll have to weigh that against 3 doctors saying that it's not warts. I don't think it looks like warts, but looking at a few pics isn't a good way to determine that.