Bug Bite!?

saturday afternoon Jack was running aroun dplaying in our yard. He loves to dig etc. Whne he ran back on the deck to sit near us, I noticed on his groin a raised redden area. He laid down for me and I was able to exam the area. It appeared to be a blood blister--- I wiped a napkin across the area to check to see if it was bleeding. It was not. My thought was a bug bite. We had noticed wasps on the deck and of course with his diggin I figured he may have bene biten by something in the dirt. A few hours later this is what the area looked like. He is not bothered by the area--no likcing or scratching and he allows me to touch the area. I did apply neosporin to the area.

Im thinking of giving the vet a call this morning--

Anyone have any thoughts on what it could be? I did have a friend say possible hot spot--but like I said there is no oozing from area and it is now flat. He is not bothered by it at this point.