Help…

Schedule a pediatrician appointment or talk to them at your next one. It's entirely normal, but a pediatrician appointment might help sooth some of your anxiety. If it's not just normal spit up, it sounds like reflux to me, so my tips are to try to feed him as close to upright as you can, and sit him up after he eats and keep him sitting up for roughly 30min to an hour. Also, I think there are some medications your pediatrician can prescribe for him if you think it's that bad but I'm not sure

If formula fed, it could be wrong teat size. We kept trying to upgrade to the next size as recommended but every feed she was being sick.
6oz every two hour is also a lot, I would recommend stretching it out another hour, that could a factor. It could be too much, remember a baby’s stomach is about the size of an egg. Baby’s at 5 months should be having five feeds of 6oz bottles in a 24 hour period.
Reflux is normally major amounts and therefore baby struggling to put weight on.