I'm sorry to hear about your female Nala.
I know how it is to loose one. I also had a Pit named Bentley before, a female.
Do you have a trainer that you normally go to or a good one in your area you could consult with?
I'll just start from the top. Some Pit Bulls can develop a fight drive as they mature meaning they will be prone to dog aggression. This usually starts to appear around 1-2yrs of age although it can be sooner or later. The dog can have been great with all other dogs before not showing any DA tendencies or dislike for other dogs. Then one day they might show a desire to fight with other dogs, it is usually more characteristic for them to get stiff and stare, or wag their tail while whining or possibly even making a crying type sound. Some will growl and screech often a higher pitch type sound though. Although Pit Bulls can have this predisposition not every one will have it/show it and not every Pit Bull who exhibits a DA reaction will be because of this reason either. While it is something you should be aware of I'm not quite sure this is what is happening in Bently's case.
It isn't uncommon for some Pit Bulls and even other dogs also to get along fine with their housemates and dogs they know but not like strange dogs.
It sounds more like Bently was unsure of the situation which is why he growled a warning to the other dogs. He might have been nervous and insecure in a situation with a bunch of strange dogs running around and running up to him that it put him on the defense. Also if you are nervous (I'm not sure if you were nervous at that time?) Bently can pick up on this and it will also cause that reaction. He is unsure and confused getting a reading from you so he thinks something is wrong which is why he acts out of sorts. A lot of dogs don't know how to act in such situations either. A place where there are a lot of dogs running loose or some leashed and some loose is a good place for dog fights to happen no matter what breed the dogs are.
You can try to introduce him properly to some other dogs like friends and family members dog to see how he acts with them.
If he really isn't going to like other dogs it is best to find out this way rather then when he is loose with another dog and attacks that dog, leading to a serious fight.
From the sounds of it though it seems like you might be able to work with him if you find out the source of his actions and work with him in a positive way. Were the other dogs loose and him on a leash. I would not suggest letting him run off lead but with all the other dogs running around him it could have caused the reaction too. He could be being over protective of you as well. Or have some fear aggression issues that are showing up. It is really hard to say without seeing him. I think test him out again in a calm situation, not so chaotic with known dogs and see how he acts. Also look for a trainer in your own area who can help.
