I think fly bit me. should i visit doc? or wait for any specific symptoms?

Insect bite: I don't think that house flies bite. Deer flies and horseflies have painful bites. I would clean the area with soap and warm water. Are you currently experiencing any symptoms? Is the area particularly red, warm, swollen, painful or tender? If you have no symptoms, I would monitor it for now. If you are having problems with it currently, consider making another post with more information.