I've been excersing for 7 months. I've lost 20lbs. Recently I increase my treadmill incline severely to work off the weight quicker. The underside of both breasts are very sore. I started using a "high impact" bra but no change in soreness. I stopped exercsing 3wks ago but breast are still sore - not as much but still sore. Since I've had soreness for over 6wks I don't think its hormonal. What could be the cause?