5 month old will not sleep...help

My baby is 5.5 months old and the past week has been hell!!!! He was only waking 1-2 times a night. This past week it was every 2 and a half hours, and last night was every 1 and a half hours!!! I am so exhausted I feel like I can’t function. I don’t know what to do. The only way to get him back to sleep is to nurse him, but I don’t want to start getting into the routine of nursing him to sleep again (I finally broke that about a month ago). But at the same time, I’m worried that he actually might be hungry so I’m scared to not feed him. When I go to his crib and hold his hand or rub his chest he stops crying. But as soon as I leave he cries again. Randomly this morning at 5am I fed him and he was wide awake. Around 10:30 he had a 3 hour nap (which is unlike him...he usually only naps 30-45 mins).

Any suggestions? I’m dying over here. I start work NEXT MONTH. I thought FOR SURE by now he would be sleeping through the night as everyone told me around 4 months their babies started.