I have had pain in my stomach for more than a month early on my stool had mucus in it. I do not have a fever. Have a lot of gas and belly feels full. I have had bouts of very loose stool but not watery some times I can't go even though I fell I need to not constipated and some time i have to go up to 7 times a day, and when I go I fill up the toilet bowl it smells very bad. There is no history of cancer in my family. What would cause this?