What Is The Cause And Treatment For IBS?

I suffer from IBS. I have had a colonscopy and endoscopy in 2013 (I have one every 5 years). I had several polyps removed, tested that came back no cancer. I suffer from abdominal pain and cramping, bloating, constipation followed by loose stools then direarrah (sp?). After the direarrah, there is mucus (jelly like substance) then nothing but water. Today I had to leave work due to the severe pain and watery stools that leaked and soiled my clothes. I am at wits end and I need answers. What do I need to do? I spoke to my GI doctor and they can not get me in until Thursday. He did say that if I felt the need, I could go to the Emergency Department. I asked what could I take for the pain and the nurse said he did not say. I am worried that something serious is wrong. I had a paternal aunt that died from UC. Please help! Thanks Kim Nix. P.S. I am 50 year old now.