Projectile vomiting

My little one has had 3 bouts of vomiting today. It had been projectile and quite a bit. The first time I thought she over ate. She was on my breast a long time. I kept her upright for a half hour after her next feed but and hour and a half later after her nap she vomited again, this time it was mostly clear liquid with a small amount of curdled milk. I have never had her vomit clear before. No fever, not fussing, still has an appetite so I don't think she is sick. Anyone else had this randomly happen? Is it just overeating?