Welcome to the site!
Have you seen a doc yet? Anytime your bowel movements change you should consult your doctor.
It's actually not that strange to have to go to the bathroom right after, or even during, a meal. As soon as the food is put in your mouth, your brain triggers a response to the digestive system to jump into gear. For some people it can cause almost an immediate BM. It happens often to those with IBS. I think most doctors attribute it to having an "over sensitive digestive system."
The clear film you're talking about
sounds like mucus. That too is common with IBSers. However, if this is new to you, you should definitely see a doc.
The pain in your abdomen could be spasms. Again, that too is common with IBSers. Yet again, if this is new, you should see a doc. There are many antispasmodics on the market your doc can look at prescribing. In the meantime, many of us have found relief by using a heating pad. Between menstral cramps and IBS pain, I use mine a lot.
Some signs of gall bladder issues are burning poops, or heartburn, or even chest pain. I'll see if I can find the Gallbladder post and bump it up for you.