PopiChulo, I think the reason you haven't got an answer is because no one really knows. If your nips are getting sore and your on 500mg of test and 500mg of Decca the first thing I'd ask is are you on any kind of anti-e?? Then the first thing I'd do is get some Nolvadex as that will help with the current circulatory estrogen in your body, not by getting rid of it but by binding to the receptors that estrogen binds to. I'd then look into getting some arimidex/liquidex so that you can keep down new levels of test aromtizing into estrogen. If none of that helps then I'd look at the vitex.
Also, a lot of guys are discussing this topic as it applies to fina, although I believe it should also apply to decca as they can both have progesterone related gyno sides. This thread is a sticky called "Fro. Prolactin, PR, Fina. Help with answers". Just look at the top of the Anabolics page.