Advice?

My baby boy just hit 4 months and has been inconsolable the last week now. At his last appt he was prescribed baby pepcid because she did not see anything wrong. It has worked up until now. He almost always throws up right after he gets it. I feel like he could be teething but I've been told it's too early. Is he just hitting a developmental milestone?? He has his 4 month appt tomorrow but I'm not sure what to say. I know.babies cry but he is usually so happy.