@KristinMarie - I noticed these on Bea when she was a puppy and it turned out to be the beginnings of seasonal alopecia. In contrast, I take Bo in for what I think is an infected puncture wound on his cheek (from Bea chomping on his face) and he gets diagnosed with demodex mange! I would have never put that together!! I think what everyone is saying is that typically - in most cases - mange starts on the face - not the body. You are right: avoiding dips like you've described; absolutely. I think the best thing to do ALWAYS is go to the vet. No one in their right mind would 100% trust their bulldog's health and well being solely to the opinions of a forum; regardless of how knowledgeable we are here - and we are! Collectively, we are a force to be reckoned with!
Oh - and Hello from a fellow Washingtonian!