I have a lot of fat on the sides of my breasts/under armpits. off & on i experience discomfort on either side then it goes away for a few weeks then returns. no masses felt and pressing on it doesnt make it worse. main exercise is walking?

Hard to say: If the sensation comes & goes, it may be that the area is being rubbed somewhat when you swing your arms during walking. You might consider trying a different type of bra which has broader sides & softer material. If you do feel a mass at some point or there is significant redness, or pain that does not go away, definitely need Dr exam.