Chills and hot flashes!!

I'm 6 wks and pretty much since I knew I was pregnant I have been chilling and having hot flashes. It gets really bad at night but lasts all day. To top it off I'm extremely tired, like I can barely keep my eyes open during the day. This will be #4, I have a 5yo, 3yo, and 22mo. I don't remember having these symptoms before. I keep checking my temperature because I feel so hot! Lol but it's always normal. Anyone else having the same issues??