We hardly ever (read never) flea our animals and they don't really have any issues. I have an issue with the expensive, smelly and strong flea control products that vets sell. I have found that some essential oils work just as well and don't have any side effects.

I would suggest that maybe something in the river got to him or maybe one of the bugs that are thriving in the current weather conditions? Also sometimes dogs do get nervous or stressed when away from their owners and pick up a bad habit of licking the same place. Could it have been that?

Give your puppy cuddles from us and hope he gets better really soon.