PaulaA
I am sorry to hear about your fears for your Dad and what is happening to you all.
You do need to be really careful when the person could become aggressive
If at all possible, try to make a safe place indoors where you can lock/bolt the door on the inside, have access to a phone so you /mum can phone for help, this would probably need to be the police.
They are very good when they know the person is ill.
The only way to start finding out what is wrong with your dad is via the GP. It's a good idea to secretly from dad keep a diary on the problems dad has , is causing aand get this to the GP.
Their are a few things that could be causing this that are often easily treated, a blood test will show up if he is lacking something that can cause symptoms of Dementia ie low in Thyroid, Folic acid
In the meantime this old thread may help to defuse a difficult situation
It may not work but if it does it wont work all of the time , its also not an easy act to follow
http://forum.alzheimers.org.uk/show...ionate-Communication-with-the-Memory-Impaired
Personally i wouldnt try to force Dad to go to the GP, as he may dig his heels in and or become nasty, unfortunately many of us need to learn to tell a white lie or resort to subtrifuge, ie getting the GP to call him in for say a well man check
I hope this helps