Has anyone had any significant bowel changes like mucus or blood in poo since going GF? If so - don't sit on your hands worrying. Get to a Dr ASAP. It's normally a stomach bug/ Haemarroids/ fissure yet it's better to be safe than sorry.
Symptoms to be concerned about:
Bleeding from the bottom or blood in the poo
A change in your bowel habit lasting more than 3 weeks
Abdominal pain especially if severe
A lump in your tummy
Weight loss and tiredness
Often Drs will do an external exam, refer you for a CT or Colonoscopy if they need to understand better what is going on.
Here's some handy sites for more details: