What to do about neck/shoulder/back pain- can I use pain pill and topical cream?

Depends. On what's in the topical cream. If you're using prescription topical cream like voltaren (diclofenac) gel or PENNSAID along with medications like naproxen, ibuprophen or others, then it could hurt your stomach and or kidneys. If you take herbal creams, it shouldn't be an issue.