Liquid aversion in 4 month old

Wondering if anyone else has a similar experience. Baby boy is 4 months old he is 95th percentile for length and 89th percentile for weight. He was born tongue tied and lip tied, he has his tongue cut and can even stick it out now. Pediatrician ENT didn't think the lip was anything to be concerned about. He is mostly all breast fed and an occasional bottle (advent with air flow insert with breastmilk.) He projectile spits up all day and night. I have been begging his pediatrician for medication as I believed he had acid reflux and doctor kept saying he was just a happy spitter. Baby has had blood in his stool now and the doctor finally put him on medication. Seems to be helping. The issue is baby is always choking, he cannot go on his back, has to be elevated, even in his carseat he chokes it is terrifying driving or asleep at night in his bassinet. Doctor now thinks he has a sensory aversion to liquids and is sending us to a speech pathologist. He believes baby needs thickener in his milk. Has anyone done this going from almost only breastfeeding to bottles and adding thickener for a 4 month old?