Dear K.,
Your description of Evan sounds exactly like my description of Jonathan's behavior at that age. I actually took him to a nutritionist (specifically because of the frustration and redness accompanied by gas) and in his case, he needed some water. I gave him a little spring water in a bottle for a few days, letting him drink as much as he wanted, and that was it. He's been fine ever since, though I still offer him water every so often to see if he wants it (he's an exclusive nurser as well).
My pediatrician recommended holding him up, like over my shoulder, and just gently rubbing his back for a few minutes after he ate, to help him digest the milk down into his tummy. I noticed a difference in the "congestion" sound when I did this. I wasn't actively trying to burp him, so he stopped spitting up as often, it just gently moves air up and fluids down.
If you want to see a nutritionist, I highly recommend Dr. Susan Player in Clearwater. She is UNBELIEVABLE with kids and infants, I actually go to her first with concerns now, instead of the pediatrician.