My 3 month old baby suddenly doesn't like to take naps. Even if he does nap, he will wake up 15 to 30 mins later and he will keep yawning and scratch his head and ears. Obviously he is tired but it is just so hard to make him sleep. I hope he can at least sleep 3 hrs during daytime. But adding up he is not even sleeping 2 hrs. It's very tiring to keep making him nap. Is this just a phase? What can I do because I'm afraid he will be over tired.

He could be teething because he is scratching his head and his ears. The discomfort from teething also makes them difficult to stay asleep in naps. Teething symptoms can appear many months before even the tooth starts to sprout. If not then he could be over stimulated. Over stimulation occurs when the naps are stretched too far apart and babies find it difficult to fall asleep. Sometimes it happens due to scheduling issues or inconsistency. If he's not too cranky I wouldn't bother too much about it. You could try to babywear to improve sleep quality as he feels secure near you.