try increasing the AI first, either the aromasin to 20mg or AIFM to 4 pumps or you could bring aromasin to 15mg and AIFM to 3 pumps.
the fact that you have used higher doses of nandrolone does not necessarily mean that this lower dose is not now causing problems (its the repeated use of progestins and age that seems highly linked to issues), however that is a pretty low dose.
if increasing the AI does not stop itchyness, would add bromocriptine (parlodel) or cabergoline (dostinex)-- selegiline is also an option as is wellbutrin (zyban).
you can also try increasing the AI again, and even if the issue is prolactin or progestenic it may eliminate (may not will) it (but it also may cause issues because that may drive estrogen too low).
you can also try direct application of AIFM to the nipples, 1/4-1/2 pump per affected nipple. this seems to help a lot in many cases.
its a complicated balancing act at times, because you dont necessarily know "who" is causing the problem.
as a note- generally reccomend that everyone who cycles keep a couple items on hand.
two AI's (AIFM or aromasin for general use- though as you have you can use both- AND letro- its the strongest and sometimes you need that level of suppression, dont generally reccomend it for consistent use, but some people need high level suppression- so dont reccomend against it either)- also if you do use letro (or even sickly

arimidex) its highly reccomended that you taper it with aromasin or AIFM to avoid rebound.
clomid and nolva (though generally only reccomend clomid for PCT- no frontload- and reccomend against nolva if any progestin is involved or was recently used)
at least one dopaminergic- like selegiline for general use, though a lot of people like bromocriptine (there a lot of love and hate it) or cabergoline (wellbutrin is not commonly used but it is a dopaminergic)