It's not an oil build up. Oil doesn't just travel around in the muscle freely. Look at the people who abuse SEOs... they wouldn't have hard lumps and scar tissues the way that skeletal muscle is comprised.
Gynecomastic tissues travel behind the areola in a non uniform fashion. It seems that there is glandular tissue or perhaps some fatty tissue that's puffing up as a result of aromatization of the hormones you're taking. Start hitting it up with some real drugs like letrozole. SERMs are fine and dandy but they are weak. It will stop estrogen/estradiol from binding to tissues in your breast but it will not bring down the inflammation that's already there. You need to eliminate estrogen from the picture to have a chance at bringing down the inflammation and inherent pseudo gynecomastia that's developing.
Personally, I run low dosed AIs so that I never have to blast my body with a ton of AI like letro. It's very harsh. Bad for the lipid profile, suicide for the libido, makes you tired, not as energetic (at least in my case, I get very lethargic), etc.... next time treat it with a SERM at the first signs, then perhaps a mild AI. Only suicide inhibitor that I've used was UGL aromasin and it did little to nothing, but human grade AIs that eliminate the aromatase enzyme have had good feedback. If you could get some hands on legit aromasin that would also be helpful.
Sorry for the fragmented grammar, was running back and fourth and I have no contacts or glasses at the moment. Bed time. Good luck, nucka. Keep us posted.