New to IBS

Hi,I was just diagnosed with IBS. My symptoms are, lots of gas, lower left abdominal pain sometimes lower right abdominal pain, cramping, severe urge in the morning to move my bowels, diahrea, constipation, nausea.I only normaly move my bowels in the morning. I get this severe urge and it is usualy diahrea. Sometimes it is constipation and I try to go but only a little, then about 10 mins after that I have bad diahrea. It is realy strange.The doctor also checked me for Celiac but that is fine. He also told me to stay away from dairy due to the fact it can make you worse. I have and have noticed I don't get nauseas as I used too. He also put me on NuLev which I take 3x a day.I do notice If I eat Popcorn I get sick with gas cramps and lower left abdominal pain.My Gastro Dr. is going to do a colonoscopy on me on the 21st. He wants to check for inflamation and Diverticulitis?? Does anyone know of that disease??He also has to check to make sure there are no polyps or cancer due to the fact my grandfather had colon cancer at the age of 41 (I am 38) and my mom had polyps.I had a real rough day with this condition yesturday. Kept switching back and forth with Diahrea and constipation and lots of gas and pain. This condition is horrible. It is very depressing. I am tired of always feeling sick !!!Anyone have any suggestions???Thanks for listening !!