My daughters teeth started decending when she was about 2 months old! She's 3 1/2 months old now and I can feel the little teeth starting to poke through!

When my daughter is having trouble with her teeth, she cries (gee, weird eh! :P). If she's hungry, she'll try to latch on to the breast, she'll suck for a moment then come off crying again. When this happens I know its her teeth and I put some bonjella on her gums (i know she's under 4 months but I got permission from my GP). Is baby drooling a lot? Sucking his bottle then spitting it out or chewing on it? If he's just off his food, it may not be teeth (though I'm certainly no expert).