husband wakes up screaming?

my husband has terrible nightmares all the time, he's had them for years he said about things he doesn't even want to know about, he also has childhood abuse that has lead him to having PTSD. he has nightmares every night, it never stops and he wakes up screaming from them on days where he's really stressed, like to the top of his lungs like when people have night terrors but he always remembers his dreams so It can't be night terrors, what is this? sometimes it's so bad he doesn't even want to sleep and will purposely stay up till he cant stay awake anymore. I've tried to get him to see if he wanted to see a doctor about it but he refuses as he's tried in his past and it didn't work, I don't know what else can be done for his nightmares