My poodles sudden aggression problem

Question
Hi, I have a 6 year old standard poodle, that we rescued when he was 1.  He as always been the ideal dog, and loves people.  We socialize him all the time, and he loves and is protective over my kids.  Just recently he has begun to grow at the kids if they get too close while he is sleeping or just relaxing.  I always confront him as soon as he does, with a firm "NO, be nice" and then have the kids pet him.  Latley his growels have intensified so I try to keep the kids away when he is napping.  He as also snapped at three different people while we were on walk, just this past week.  One person was a child, and he went for her face, then coward behind me.  This is totally out of character for him, he is a big part and our family and loved very much, I don't want something very bad to happen.  What should I do?

Thank You,
Brooke

Answer
I had a toy poodle do this at the age of 14 years.  He would rush you agressivly after being wakened from sleeping.  We found out he had a brain tumor.  Usually a sudden drastic change in behavior is a result of some hidden medical problem that could be causing him pain.  I would take him to the vet and tell the vet what you are experiencing and ask for help.