What should i do for a lump in face muscle / parotid gland?

Surgery: Almost certainly needs to be removed by an expert. Or at the very least, observed repeatedly by that same head and neck surgeon.

Parotid gland: A fine needle aspiration of your parotid gland may be beneficial prior to surgery, to enable the surgeon to have a better idea of how to plan the surgery and to know the nature of the lesion that is present.