Passed out at 12 weeks 3 days

Last night, I was at a Halloween event with my fiancee and mother in law. It was nothing big, of course no roller coasters or anything. Just a few houses and carnival games. After arriving we went through one house and went to stand in line at the second. I had just eaten, and drank a large lemonade and it was not hot or crowded but after about 10 minutes of standing I started to feel dizzy and unwell. I quickly dipped under the ropes and tried to make it to the picnic tables to sit. About halfway there, the sides of my vision began to close in and I leaned against the nearest pole, looked at my fiancee and said, ''I'm going to pass out. " The next thing I remember is waking up on the floor with my fiancee and mother in law looking terrified down at me. I apparently last consciousness for about 30 seconds but never closed my eyes. Once I could stand, we quickly headed home. Luckily he caught me before I could hit the ground hard and I don't think I hurt the baby but I am so scared. Going to see the obgyn this morning to confirm all is well. Has this happened to anyone before ever??