Formula question!

I switched my babies strictly to formula at 1.5 months (wasn’t producing enough for twins & I mentally couldn’t do it any longer) but ever since I’ve done that, they both wake up screaming out of the blue constantly trying to poop and normally can’t, unless I massage their tummies & give them warm bathes to help them work it out. They’ve been super gassy too. & they are dealing with acid reflux which they are on medication for already 😭

My boys are on Similac Neosure, & I’ve recently started mixing half & half with that and Similac Pro Sensitive but nothing has changed for them (Dr suggested Karo syrup which has helped a little bit not much)

So I’m wondering if anyone else has dealt with the same thing and what formula has worked best for your baby?

Thank you in advance 💕