What could cause my baby to do this?

He's 3 months old, and has always been a good sleeper...I put him in bed, with pacifier and he's sound asleep in no time. At night he would sleep 8-2, feed, and continue sleeping till about 6/6:30. Suddenly, he's waking every 10 min. during his nap and is inconsolable. At night, he wakes 5-6 times and screams as though he's hurting...I have to pick him up, calm him down, and put him back in bed. I'm exhausted. During the day, he's got his fist in his mouth and is drooling like crazy...could teething be waking him up like this? It doesn't happen every night, but maybe 3-4 times a week, so I don't think its that he's spoiled. Any clue?