Why is my 1 year old Beagle showing signs of violent agression?

My Beagle is a little over a year old and is showing rabies-like symptoms. I've done some research and my dog has been showing some of the listed symptoms of rabies, but I'm not totally sure. Today AND 3 days ago he, for no reason whatsoever, attacked 3 people including my mother, grandmother, and brother. He has been vomiting profusely, and attacks people with no provocation or reason whatsoever. I believe it might be the result of a new kind of kibble he is eating (he used to eat human food) but I'm not completely sure. His violent episodes usually last 15-25 seconds, and include gnashing of the teeth, intense growling, bloodshot eyes, and no sense of self discipline or pain (we slap him right above his tail for discipline). Any answer as to why this good-natured, cute dog has insane episodes will be helpful.