What's wrong with my Beagle?

I have a beagle, he's 2 years old. He's not acting too funny, but slow i guess. He didn't eat all his food right away tonight. He looked at it and walked away. Finally he did eat it all. I gave him a raw hide to chew on and it took him some time, longer than normal. At first her kept licking it then finally he was able to eat the whole thing pretty fast. I noticed while he was chewing on it he opened his mouth then it locked for a moment or two then went back to normal. It happened a couple times. I tried looking down in his mouth to see if i saw something and I didn't. I know my mom has been taking him for walks everyday in this hot weather for the past three or four days. I thought maybe it was taking a tole on him right now. Also he dug up an old bone he buried a while ago. I thought maybe it upset his stomach a little. I just noticed when he was outside he had some druel on him but nothing excessive. My mom noticed some again when he was inside, but again nothing major. Also i noticed he smacks his lips like he's got peanut er on the roof of his mouth but we never gave him any. the licking isn't excessive just when he lifts his head up. He eats his treats that i gave him also and anything else he was given. So his appetite isn't going away completely. Help I don't know what's going on. This just started today - July 18, 2010