How long have the bumps been there?Do they seem itchy?What do the bumps look like?
What breed is he?
Thanks for answering my questions.
Without being able to see your dog in person, it's pretty much impossible to tell you why he's looking the way he does or what could possibly be causing it. The list of things it 'could be' is nearly endless: allergies, infestation of parasitic mites (mange), thyroid problems (although he's awfully young for that!) or a bacterial or yeast infection are just a few. My suggestion is to call your regular vet in the morning and schedule an appointment for them to see your pup and see what they can determine. They'll most likely do a skin scraping of the affected areas (where they use the edge of a scalpel blade to gently scrape off the top layer of skin, looking for any mites), and possibly run some blood work to see if there is a thyroid issue. In the meantime, you can give a little Benedryl at the dose of 1-2 mg per pound of body weight (meaning if your dog weighs 20 pounds, you can give 20 mg the first dose, and if that doesn't help, you can give 40 mg at the next dose) one time every 8-12 hours.
It sounds as if he's pretty uncomfortable though, so I would give the vet a call first thing in the morning so that you can get this cleared up so that he'll feel less itchy.
I hope this helps.