Low blood sugar could have caused it. Keep peanut butter crackers on you and something to drink. I have to due to my hypoglycemia. I have always had it but it gets worse with pregnancy. I also have heard many women getting it during pregnancy and then it going away after.
Those are symptoms or pre eclampsia or dehydration. I'd go in to get checked out and have your blood pressure taken.
Those aren't just symptoms for just those 2 issues. It can be anything. Just talk to your doctor and get checked out. Mine is hypoglycemia and I do that a lot but normally can feel it coming on so I know to sit before it happens. It may not be any of these things so you need to call your doctor.