We went through the exact same thing you are going through with our son. He is now 10 months, and all his digestive issues are gone. Here is what we went through/did. First we went down the list of forumulas, like you have I am sure. We tried the Emfamil hypoalergenic one first, Nutramigen. We saw no change. Then our doc told us to try similac Alimentum. Our guy was on prevacid/zantac too for reflux, and then we had to start to put rice cereal in his bottle.
Our doctor told us that Nutrimigen and Alimentum are basically the same, but they break down the proteins using a different process. he said there is no explanation why, but some babies just do better with one rather than the other. Our guy did better with Alimentum, so maybe your little one would do better with Nutramigen.
When i say he did better, I mean that he stopped screaming from gas literally 24 hours a day. Like you we tried Mylacon, and it did NOTHING. They explained to us that some babies literally can feel their gut digesting the food, and while it doesn't "hurt" they don't like it ( I don't think I would either).
I can say that around 10 weeks he was substanially better, and that is when he had been on his routine of Alimentum with a bit of rice cereal in it with every bottle, and his medication. Also, I will get bashed for this, but the reason we went to Alimentum FULL TIME was because our doctor said, keep pumping and save the milk, and try just the formula for three days. We did this and he stopped having all the problems. I know some women will say it was my diet, but by the time we did this I had cut out basically everything from my diet from dairy, to spicey foods, red sauces, wheat, leafy vegetables. I seriously could barely eat anything. Even that did nothing for him.
I agree with what most will say that breastfeeding is usually best (I did with my first child until she was 12 months), but it just doesn't work for some kids. I think my son was one.
We have just recently been able to get him back onto regular similac formula, without medication.
If you need anything else, just let me know. I know what you are going through and it is so hard. Good luck!