sno92c~sorry to hear you aren't feeling so hot
Your body just might not be ready for salads yet...what type of lettuce are you eating? In the beginning the really soft ones are the best (think Boston or Bibb) and easy to digest.
It does sound like you may have something blocked which would cause the high output of liquid...I drink a ginger ale when I feel that way and it helps to sooth my stomach as well get things moving. Strong coffee gets things moving, too!
Take it VERY slow when trying new things and only eat small quantities until your body gets used to them...and if a food bothers you now, try it again in a few weeks, and you might be surprised you'll tolerate it!
If it hasn't gotten better you may want to try a heating pad (be careful not to put it on your stoma or your incision if it isn't healed) to help things relax. If you start vomiting or your output stops please call your doc.
Let us know how it goes!