How can you tell if your baby is teething? The last few days my 3 month old has been fussy and chewing on his sleeve alot, actually chewing on everything. Sometimes he seems to whimpering like he's in pain and it wakes him up from his nap. My mom thinks he's teething but I'm not sure. Is 3 months too early to teethe? Usually, I can tell when he's hungry by stroking his cheek or if he's sucking on his hand. But, I've been having a hard time since he wants to put everything in his mouth now even after he's eaten. I think he still is getting enough to eat because he sleeps at night... its just during the day he's like this.