are you taking an AI at all ? Masteron is lowering SHBG and thus freeing up a ton more DHT into the blood stream . this is usually a good thing for Libido, unless your keeping estrogen too low with an AI.
as your androgen levels elevate you estrogen levels should elevate along with them . masteron is going to dramatically increase androgens with NO increase in estrogen conversion.
if you are taking an AI , drop it