I'm wondering if the fact the new girl isn't spayed is also having an effect? Dogs pick up on the oddest things..
I'd feed them completely separately at this point - different rooms. Your male may not appreciate sharing his space, food, toys, etc with this new girl. I'd also make sure you spend 1 on 1 time with each of them - train seperately, etc.
I do agree with getting a qualified behaviourist in at this point - big dogs can lead to big problems if not nipped in the bud immediately.