Thrush or mastitis anyone?

Has anyone had mastitis or thrush while breastfeeding? I got through the initial painful 2 or so weeks and haven't had pain nursing since. The last week and a half I have been having nipple pain while nursing. Nothing like in the beginning, more irritating and slightly painful. But today when she nurses on the one side I get a like a stabbing pain inside my breast every few seconds. Does this sound like either one of those and should I make an appointment? Appointment with my GP or OB? My daughter did have a diaper rash last week but no evidence of thrush in the mouth that I could see.