I had my sleeve July 2016 and have been thinking about getting my notebook out and starting on the pre op diet again. I am up 4 pounds and can't shake it since Thanksgiving. I lost 56 pounds and that was it but I was able to get off my insulin and all my diabetic meds.
I'm a year out of surgery and had the same problem at first. Here's a solution around 7 pm take a Dulcolax tablet then at bedtime take a peri-colace. In the morning you should have soft stools and feel much better. In time this all passed for me. No pun intended.