My dog was neutered five days ago. Yesterday his scrotum became very swollen and there is a large (larger than a quarter) red blotch on one side of his penis and onto his belly area. His lymph gland is swollen on that side as well. I took him to the vet immediately and they said it was normal--that he licked himself or was getting too much exercise. He has been monitored 24/7 but might have licked himself at night briefly without me knowing or infected it when he decided to sit on a pile of dirt in my yard two days after surgery rather than pee. He didn't have a fever and his heart rate was normal. The vet put him on antibiotics and pain killers and sent us on our way. Since, the redness on his penis had deepened in color substantially and the gland swelling has not gone down at all--in fact, it almost seems worse. In addition, there is now a red spot forming where the scrotum and penis join. Could this be something more serious than a five day course of antibiotics will take care of? What is that weird red spot from? Local injection during surgery? Under the skin bleeding?
I have attached a picture of the red spot (you can see how swollen the gland is right next to the spot) and the swollen scrotum.

