Cold sweats and vomiting

I'm 25 weeks pregnant, and a couple of times throughout this pregnant while trying to rest, I get a strong urge to vomit and I start sweating so profusely with cold sweat that it wakes me from my sleep! It lasts about 30 seconds to a minute, feeling like I have the flu, and then it goes away as quickly as it came. Has anyone else experienced this? This is my 4th baby and I've never been through this.