My infant started spitting up around two-three weeks of age. Doctor prescribed zantac. It helped a little but not completely. It tasted so bad, i felt terrible giving it to my little baby. So i did my own research. I was breastfeeding him exclusively at the time and I did an elimination diet and found that dairy was the culprit. Two weeks off of dairy, his spitup completely disappeared.
Before I found out dairy was the culprit, I had to hold him upright for atleast 30 mins after every feeding or else he would spit up all over the blanket or cry uncontrollably. Even holding him upright for that long, he would still spit up sometimes. He liked to sleep in his car seat and that seemed to help, but made him congested. I think the pressure from the stomach bending while sitting in the infant seat pushed the acid into his throat or something. Some people say infant seats are good for reflux and some say its bad because of too too much pressure on the stomache. I personally think its a bad idea, but he seemed so comfortable in it and it was the only way to get him to sleep for longer than an hour at a time.
His reflux was so bad that putting a wedge on the mattress to make it slightly elevated made no difference. I looked into getting a tucker sling where the infant lays kind of in an upright position without undue pressure on the stomache. But before I got a chance to order it, my son's reflux disappeared while on my dairy elimination diet.