Hmm, I must say I can't say I'm sure about this, but I have understood that test converts in the end always way or another, either DHT or Estrogen. Taking propecia inhibits DHT conversion, and therefore estrogen levels usually raise big time, causing gyno, puffy outlook, fat gain etc. So in the other hand if estrogen aromatization is inhibited, I think DHT levels will go higher instead. I can be wrong though!
That's just thinking, I don't know the exact explanation but it's for sure that it caused hairloss to me and that was permanent, that lost hair has not came back since.
If you put aromasin and hairloss in google, you will find a lot of topics about that too.
Usually when gear attacks your hair, scalp gets itchy and inflamed feeling.
But we need to remember there is two kinds of hairloss, temporary acute hairloss when some new drug is effecting in our body or we are going trough major stress etc., that hair will come back. In the other hand there is MPB genetics hairloss, which kills the hair follicle and is permanent.
Maybe your body is just reacting for the high anabolic effect, and dropping the old hairs because of that. Hopefully.
p.s. Don't touch propecia.