Easy Trigger!....sorry that is something Al says to me when I am pushing things too much. I really think you are trying to be 100% better faster than I would expect. Heck it hasn't even been a month. I don't care if it was lap, I still say they moved your guts around and that takes time to recover from let alone the surgical aspect. Even just get pressed on for diagnostic tests takes my guts a few days to readjust.
The gas pains will likely happen for a while until you are back to eating more normally. We have been doing lots of work on the house and turning the water off for periods. It takes a few runs of the faucet before it runs without spitting air. I look at our guts the same way. You are not putting through the same amounts of liquids and solids and your guts are still playing catch up. I know you say you are not eating much. Perhaps it would be better to try eating some more...just small amounts all day. I know this helps kick my gut back into gear when I fast for 4 days before a scope.
As for the cholestyramine affecting the gas....I don't really know that. It more binds the liquids so I am not so sure it would impact the gas. Like I said before, if you are going to start it, I recommend trying a small amount to see what the least you can use is. My bloat seems unrelated to the cholestyramine...the C I was having may have been completed unrelated to the cholestyramine as I look at it in the rearview mirror (small pun intended).