My Husband Has Been Waking Up Lately Completely Drenched In

My husband has been waking up lately completely drenched in sweat, shivering with chills and needing to throw up. The first time it happened, I wanted to take him to the ER since it has never happened before but now, it's like he wakes up all the time. We have no idea what it can be. We were leaning towards night flashes but nobody seems to have the symptoms of shivering and throwing up. What can be causing this?