Fainting?

Im almost 13 weeks and since 11 weeks I’ve randomly started having lightheaded “spells” I’ll be fine and then the world starts to go black and my ears get hot. I have to sit down and then 5 minutes later it’s like nothing happen?? When it happens I drink water and eat crackers but idk if that helps or not. Is this normal? Called my OB and I will see her tomorrow but just wondering if any mommas have any input? Could it be gestational diabetes this early? Thanks ladies!!