Red bumps - update with GOOD biopsy results!!!

Gus has a large red bump in his front left armpit and a smaller bump on the front of the arm. The large one was very small a couple of days ago ad has grown. To me it feels like something under the skin and not over. We have taken many ticks off of Gus the last couple of weeks, so it is definitely possible this is the location of a tick bite. To me it feels/looks almost like an ingrown hair. DH is really concerned about it because of all the tick bites. I'm feeling less alarmed. It doesn't seem to bother him and I wonder if left alone for a couple of days it might do down on its own.

I realize this is a vague written description, but does anyone have any thoughts about what it might be?

I told DH I would make Gus a vet appointment, so I will, but I'm always curious to know what this wonderful community thinks.

Also, what rule of the universe states that whatever dog is hardest to take to the vet will be the one who has to go most often?