When to try different bottle and when to try different formu

Our son is 5 months 2 weeks old and I recently switched his formula because he was having horrible gas that would make him scream for hours and he was spitting up horribly, even hours after he ate.
He was doing fine on the new formula for about a week but all of a sudden he lets it run out the sides of his mouth and even spits it back at you. Sometimes he acts like he is choking on it. We feed him sitting almost upright (he has always done best like that) and we use medium flow nipples. I had him on slow flow nipples but he sucked on those so hard he would collapse them and we had to pull the bottle out of his mouth every about minute.
We are using Avent Bottles and they have been working this whole time. Should I try a different formula or different bottles? I tried Dr. Brown's bottles and he wouldn't take them. I also tried MAM bottles but he didn't care for those too much either.
Any advice would be GREATLY appreciated.

Quoting Jeanine Simmons:" Our son is 5 months 2 weeks old and I recently switched his formula because he was having horrible gas ... [snip!] ... take them. I also tried MAM bottles but he didn't care for those too much either. Any advice would be GREATLY appreciated."

What formula are you using?

Maybe try the vari flow teats some bottles use? The flow adjusts with how hard they are sucking.

He is currently on Enfamil Premium. Before that he was on the Similac Sensitive and he came home from the hospital on Enfamil High Calorie (he was low birth weight)
I have tried Similac for spit up and he wouldn't even drink the bottle.

if you already tried new formula I would try a different bottle. I always like the playtex nursers that are disposable but my girls would only drink from the brown nipples. That way you can go back to slow flow and he isn't get so much at once. I know a ton of people that swear by the dr browns my girls just didn't like them.

Quoting Jeanine Simmons:" He is currently on Enfamil Premium. Before that he was on the Similac Sensitive and he came home from ... [snip!] ... on Enfamil High Calorie (he was low birth weight) I have tried Similac for spit up and he wouldn't even drink the bottle."

My LO was BF for a week before realizing my milk was not satisfying him or not coming in, I'm not sure which, I switched to formula because he was REALLY sick with Jaundice, I was so upset. But, I switched him to Similac Advance, the default the hospital will give you..But, he would eat and eat and eat and never get full, and would get really fussy. I switched to the Similac Sensitive and it did wonders, he ate on a normal schedule, he spit up less, it was great. Sorry, it's not working out for you. There's a lot of trial and error in picking formula.

I just used the Walmart, Parent's Choice bottles..I never had a problem with them, at all. Not once did they leak or cause any problems for LO. I loved them.

I had to put mydaughter on soy formula because she was spitting up a lot. We always used dr browns bottles but i tried a nuk bottle with her one day when we were out and forgot a bottle at home and she took it. I would try nuk bottles and maybe soy formula (she was on similac soy)

My son is on similiac sensitive and has never spit up we don't even use burp rags no need   and he is using nuk bottles and pacis. We love that brand. Hope you find what works for you!