I agree with Patricia Gima that some physical therapy might assist the
mother whose breasts have been hurting for 5 yrs. Something gentle, like
Traeger massage, which can very safely be used by post-partum moms. I can't
credit yeast when there are no other symptoms, altho it certainly couldn't
hurt to cut down on sugar.  But to make this problem "mysterious" and
suggest a restrictive diet is to make her situation worse.  Susan Love
describes a kind of arthritis which causes aching in the breasts, but which
is really centered in the bones of the rib cage.  I wonder what would happen
if she took ibuprofen for a week or so using mfgs directions for dosing?
Barbara