14 month old waking

My son has been on 1 nap for almost 3 months now and the transition has been a breeze. But here the past 2(2½?) weeks, he wakes every.single.night between 12-3 am screaming. My husband thinks it's just teething but this is getting really old really quick and we're exhausted! He goes down for his nap between 12-1, depending on how