Prilosec Help New to here!

My son just turned 5 months old. He was the perfect newborn. Slept from day one through the night, never cried unless he was extremely hungry! Until he was about a 2 months old, then the screaming started, He cried constantly this High pitch very painful scream! He refused to nurse and basically would arch his back and scream! We took him to ER and they said probably reflux, then followed up with our ped they said nope prob uti, so then he was on meds for uti and he seemed good… then the screaming started again. They Put him on zantac and it worked, for 2 weeks. now hes on prilosec, and it works great, but its hard for us to get it into him, bc it tastes horrible. He has only gained an ounce in the past month and is very miserable here this past week. Anyone have any suggestions for how we can get this down him? Pharmacist has nothing they can mix with it, and I cant seem to find the cocobase stuff. Ive heard of the hershey syrup? doc said they dont wanna do that unless we have too. Any suggestions I would appreciate. He is on 3 ml 2x a day. he weighs 15lbs. Do we need to up his dosage? am i not doing something right? I always prop him after a feeding and give him cereal to help the reflux. (I strictly nurse). Im hoping this is gone by 6 months. I want my happy baby back! He was smiling at 2 weeks and we called him smilin kylan. Kylan is his name. Now we call him cryin kylan. Thank you in advance! He sleeps on his belly (shhh..) in his crib with his mattress propped. He also has a horrible mucasy cough, doc said might be due to reflux? Thanks again!