Have you ever had sex? Oral sex?
If you haven't, this can't be a wart. Lots of things cause bumps, not just HPV.
If you have had sex before, it could be a wart. You don't have to have anal sex to get anal warts. Warts can appear anywhere in the entire genital area, including the anus.
If it could be a wart, let your doctor see it. If it's more of a lump than a bump, get it checked. Get it checked anyway - find out what it is, and ease your fears.
From what you describe, you don't have HPV. You didn't have intercourse, you didn't receive oral there. YOU gave oral (not a risk for HPV all of a sudden by your anus) and fingering doesn't transmit anything. The bump could be a hair follicle or something like that. I'd leave it alone and it will likely go away.