We just took our English Bulldog puppy to the vet for the same thing. The vet said it is staph infection and very common in young puppies since they are always sticking their faces into stuff. She gave us antibiotics that our pup takes twice a day and it started clearing up nicely as soon as the next day. Good Luck!
Dogs get zits to under there jaw. My boxer gets them too
The bumps are infected ingrown hairs. If you pop one like a pimple you will see that a tuft of hairs will come out with the pus. You might need to pop the major bumps and put medicine on the area. Very difficult to cure because dogs will get them from laying on floors. Dogs get them where they lay their chin or elbows on the floor and the hair rubs off to shorter stubby hair which becomes ingrown. The most permanent preventative is to get your dog a very soft bed that they would prefer to lay on other than the floor that would let their hair grow back.