Have you had any celiac testing yet? If not ask your doctor to test. Has your doctor ruled out anything else it could be? Have you had any testing done like barium swallows, ultrasounds, x-rays etc? Projectile vomiting like you describe is not to my knowledge common with celiac but that is not to say it can't happen.
Do keep eating gluten until all celiac related testing is finished.
I hope this gets figured out for you soon.