My Rottweiler Has A Bumpy Spot Under Her Arm Pit,

My Rottweiler has a bumpy spot under her arm pit, she has had it for a while now I told my vet and she said it was nothing. And today she had a tick right by it so removed the tick and noticed a black spot in the middle, so I squeezed it slightly and it was almost like a pimple. It doesn't seem to bother her but should I be consigned?