Progesterone doesn't raise prolactin but high estrogen can. If I remember rightly your estrogen had gotten too high (otherwise you wouldn't have had gyno) and so you prolactin was probably elevated too. If you were constantly checking for gyno and messing with your nipples that just makes it a whole load worse. Not saying you we're messing with them but if you were.
Tren is a progestin and that means it has good affinity for the progesterone receptor. Progesterone role in gyno is to enhance estrogens effect on breast tissue growth and lowering prolactin will do nothing to stop progesterone in doing this. Lowering estrogen on the other hand will as progesterone will not grow breast tissue in isolation.
Even if you agree with none of the above (feel free to double check my facts by the way I won't be offended), then you would agree that caber only lowers prolactin and does not lower estrogen or block the effects of progersteone I assume? If so then you will see that all you are doing by taking something to lower prolactin is to treat the symptom and not the cause (which in this case is out if control estrogen enhanced by progesterone). So again we come back to my point that the best and only really way to deal with tren is deal with estrogen either by an AI a serm or both as it is impractical to stop the progesterone effects from tren unless we want the horrible sides of mifepristone.