There is no pump, just a red circle, we just got him check at the vet prior to this appearing and he was healthy and we got him on worm meds because we are moving to germany. What could it be?

Could be an insect bite, an abrasion, a fungal or bacterial skin infection. If it doesn't get better in a few days, have your vet take a look.

I'm wondering if it is a tick bite or possibly ringworm. Only a vet can diagnose it properly.

I do remember my dog biting in that area. I forget what for. Fleas. Itch.