I have the same problem and I have had my lap band 21/2 years. I have tried everything and even ducolax didn't work. My GP actually gave me a constipation relief recipe this week and it actually started to work yesterday. Here it is:
1. 2 cups of applesauce. (I used unsweetened of course)
2. 2 cups prune juice or 2 cups of stewed prunes (purée them)
3. 2 cups organic wheat bran
Mix together and store in refrigerator. Take one TBSP twice daily .... If to much,adjust. I am hoping that finally this will take care of the problem. I know just how awful you feel. If you have any other suggestions let me know.