Flea’s will be fleas.
They (like the seasons) come and go as they please. If you have a cat or a small dog that is close to the ground or your dog just likes to run around at the dog park your bound to get them. Flea shampoo’s tend to dry out dogs skin especially with pitbulls considering there skin is so sensitive. When i wash my dogs with flea shampoo i make sure i use a soothing lavender, aloe or oatmeal conditioner/shampoo to relieve the itchyness from the flea bites and the dryness from the shampoo (and also flea shampoo usually doesnt smell to nice). Flea’s also live in your couches, blankets, and carpets, but as i said before, fleas come and go. I find in the spring time my dogs will go from no flea’s to just covered in them, and after a week or so its like it never happened. I hope you get your flea situation under control, they drive me and my dogs nuts so i hope you find a good solution!