A trip to the ER to kick off the 3rd trimester! Ugh!

Yesterday I posted about feeling feverish and mild flulike symptoms. The fever was low and Responded to Tylenol. So I called off work and went back to bed. I woke up mid morning feel COMPLETELY fine and decided that since I felt ok and my fever was gone that I would head into work for a half day. I got a few miles down the road suddenly felt like I was going to vomit. I pulled over but nothing happened. It passed after a minute. Decided work wasn't happening at that point and actually was going to drive myself to the DR office instead. Didn't get very far... Soon after I got an intense feeling of dizziness and thankfully I was able to pull over in time before passing out. I had to call an ambulance when I came to. At the hospital they couldn't really figure out the problem. My blood work showed low potassium and magnesium levels. They gave me an IV with those in it and the. Discharged me believing it was an isolated incident.  I am 28 weeks pregnant so the women's hospital also did a non-stress test and everything checked out. Needless to say it was a crazy, scary day! In wondering if anyone else has ever had low levels like this or experienced dizziness?? I'm a freaked out!!