Just dx'd with diverticulitis. started on amox-clav today but have upper and lower back pain as well as waistline pain. is that normal?

Give it more time: For most infections, including diverticulitis, it takes at least 2-3 days for symptoms to improve after starting antibiotics. And often symptoms may worsen or change for a couple of days. If the new pain is severe, or if you have new or higher fever, discuss with the doctor treating you. Otherwise, contact him or her in a few days if symptoms are continuing.