skin can become quite sensitive with meds, we have seen it before with other members but not particularly this part of the body. maybe the shirt is rubbing them and i would try to wash a soft undershirt with softeners, maybe even sleeveless undershirt, so something soft is between skin and shirt maybe that will help.
It never ceases to amaze me how so many doctors don't know such things. I'm male. I've had numerous experiences over the years of breast pain & sore nipples being the side effect of medications -- even with some medications that my doctors had said "weren't supposed to" cause breast pain.