Update: anyone know why this keeps happening?

My son will be two in September. For the 4th time today within the last couple of months he projectile puked 3-4 times and has a fever of 103. Every time this happens he has a fever. I don't know what to do. The last time we took him to the doctor they said he was just fighting off something viral. I'm becoming very worried that something could actually be really wrong.