Welcome to HealingWell!
I put a subject to your thread... Hope you don't mind. I think you'll get more replies that way.
Do you eat before bed? I noticed that if I sleep with a full tummy I wake up so nauseous and end up in the bathroom with D.
Are you taking any probiotics?
Have you tried taking an OTC antacid med, like Tagament or Prilosec? Over acid production can cause a lot of nausea. I had an EGD done and even though the doc didn't see signs of acid reflux he still thought I produced too much. Once I started on Prevacid my nausea went away.
Regarding the Levsin... Have you told your doc it's not working? There are plenty other antispasmodics out there to try.