Projectile Vomiting ! This can't be "normal"

Baby girl is 8 weeks, about every 4 days she projectile vomits (not spit up) ... A LOT. I can't find a correlation other than the episodes are  always in the evening. I prop her upright , burp her and just out the blue she blows. Its all over, clothes, blanket, sheets soaked. The volume is so much she has aspirated it and really freaked her out.. as well as I. I took her to the dr thinking she had a floppy epiglottis but he didn't seem concerned said maybe it was GERD. She isn't fussy beforehand there are no warning signs. Could I be overfeeding her?  Am I over reacting, is this "normal"?!