Thanks for using JustAnswer.com.
What this sounds like is a surface skin infection. Small little raised pink bumps that come and go, sometimes get crusty, sometimes have hair loss can be very common in dogs. They often show up around the ages of 2-5 years of age. If they are not itchy and not causing major hair loss then they can be watched for awhile. If they begin to spread badly, become itchy, or a lot of hair falls out then a trip to the vet is warranted. A simple antibiotic will take care of the problem usually within a couple of days. Not a lot you can do at home, benedryl is ok but since this is often associated with low numbers of bacteria, usually antibiotics are required.
It is true blue dogs having weaker genetics often can have more issues like skin problems. However spring and summer related problems are the classic symptoms of early stage seasonal allergies. Most of the time these bumps are seasonal allergy triggered. If the bumps are not terrible they can be watched and will often go away again in fall and winter. Seasonal allergies have a tendency to get worse every year.
Bathing will sometimes make the skin a little dryer but unless you are bathing daily it likely didn't make the problem worse.
As for your second question the answer is both.
The way it works is that the seasonal allergies start --> the allergy causes a weakening of the skins immune system --> the weak immune system allows minor bacterial infections --> the minor infections cause the bumps.
So in essence through a process in the skin the allergy causes the infection.