Sharp irritating skin pain in the side. Could it be zoster coming back?

Recurrent zoster... ...Is very rare, but it does happen. Treatment (with valacyclovir or famciclovir) would be the same as the first time; but there are other possible causes, such as herpes simplex, a pulled muscle, a cracked rib, or even an internal issue. You should see your doctor and get this sorted out.