Just had Bubba at the vet on June 30th with the same problem. He does this every year when it gets hot, and Gold Bond Powder always took care of it, without vet visits. But this year it looked a little different and started going down the insides of his front legs as well, and he was licking on the inside of his front paw as well. The vet took a swab, and he was starting a yeast infection. She put him on Acidophilus, which you can get at a pharmacy or health food store, which helps with yeast infections, same stuff is in live culture yogurt, in capsule form. Also gave us prescription wipes "Aalaseb Pledget Wipes" that we blot the areas with twice a day. He is already so much better.
Just watch and be sure you aren't developing a yeast infection.