All other blood work is normal. can you still have polymyositis even with normal blood work?

Very rarely: That is extremely rare but polymyositis can occur with normal muscle enzymes. However, the clinical picture must fit and the EMG and muscle biopsy should confirm the diagnosis.

I'd be surprised: I've devoted my life to lab medicine. Only if the history and physical exam are almost screaming "Polymyositis!" would I consider proceeding with muscle biopsy / EMG.