Bad phase?

Hannah
My little boy is 3 months and the last few days has refused to nap, wants to nurse nonstop and cries if I sit him down or lay him down. He's not hungry, he's exhausted and he will fall asleep but as soon as I lay him down his wakes up and starts crying. 
Is this a phase he's going through? I'm at my wits end. He doesn't sleep good at night because of gas and reflux so he needs his naps.