My son's behavior is the exact same way when he is teething. When he cut his first tooth I was seriously frightened of him, not knowing why he was behaving that way. My angel becomes a demon! He has 6 teeth now (just popped the last one yesterday) and has gone through this with every one. I've noticed that along with the behavioral change, he would always have a bout of heavy loose stool exactly 2 days before they cut through.
I read this somewhere: "You can't do anything about your child's behavior while teething. The only thing you CAN do, is offer them plenty of things to chew on (the harder the better) to help toughen up the gums, and make the process as quick as possible." It HAS helped.