Aggressive cat

Question
In brief - I have three cats 2 female and 1 male for years.  The male just had his ear canal removed to alleviate a chronic ear infection (he lost his ear before I found him).  Anyway, I really think he's a new cat - always a love but I'm noticing that he's become super aggressive to the female cats.  So much so that he's attacking them.  He scares them so bad they run from him if he's near and one of them was so scared she peed right on the floor before a horrific screaming attack.  None of them have ever done this before.   This never used to be the case.  I immediately separate them taking Vincent (the aggressor) and putting him in the bathroom for 5-10 minutes.  Does that even make sense?  I'm worried this is happening when I'm not home to break it up.  What can I do?  Give him?  I want them to have a nice life and not be scared or rounding the corner in fear of getting jumped.  

Thank you-  

Answer
I would take him back to the vet that did this surgery and have him check him over for some kind of nerve issues involving his ear. Cats that act like this are usually in pain of some sort or are just sorting out how they are feeling after a huge surgery like that. Sometimes its just the smells are different to them so the females might smell different now.
You might want to get some Feliway and spray it around the house. It is a pheromone that helps calm the cats and tells them all is well.
In any case, the vet might be able to ascertain how much pain he is in or if it is due to pain or an olfactory issue. He just might not be able to smell the same way.
Take him in, try the Feliway and see how it goes.