I am not a physician so I can not tell you what is wrong with you. I can tell you some of my colon history. I have irritable bile syndrome, history of duodenal ulcer, one colon polyp - benign and removed, several stomach polyps - benign and removed, diverticulosis, a severe attack of diverticulitis, twisting of bile when I had an hysterectomy, partial blockage of colon, internal and external hemorroids, and hiatal hernia. I had hemorroid surgery. I have other health problems, but I'm just mentioning my colon history.
First always take your pain seriously. Dark colored blood in your stool can be cancer to Chrohn's disease. How much are your bleeding makes a difference so does what have you eaten lately. Light colored blood can mean hemorroids. Severe pain can be different things. But severe pain in your colon can be some blockage or just an attack of colitis if it is followed with so many hours of diarrhea. Any one who has gone through this can verify this. A gastroentrologist is needed to do tests to find out the cause of your pain, if it is in your digestive system. A trip to the er is well made, but following up with a gastroentrologist is advised, even if the tests are unpleasant.
I'm tired of my left side hurting all the time. Some times it swells. I think gas distends it. Even when I go, I may still have more inside me. When I hurt a lot, that is usually the reason for the pain. If I hurt for any length of time, I need to take something to make me go a lot. Not taking fiber is usually why I hurt, but I hate so much taking it. When I'm really bad because I haven't taken the fiber like I should, taking a couple of fiber supplements or fiber cereal just isn't enough. As long as you can go, you should be o.k. I've been fighting fiber therapy for years. You would think I would learn by now. Eating spicy foods is another reason. I once got a rectal ulcer by eating too much roughage. I had to stay in the hospital for a week. Ate too many cucumber seeds. Eating too many seeds like in eggplant and eating popcorn effects my diverticulitis. Tomato products effect my stomach. Too much roughage is overrated. Little bit of everything is healthier.
If you still hurt and get no satisfaction with your trip to the er, don't ignore your pain. Doctors like to blame everything on irritable bile syndrome. They say it to you like they are saying - well just live with it. Maybe that is true, but make sure before you do. Doctors don't know everything. They just go by symptoms. Unless you are in a definite crisis, they won't do a endoscopy and colonoscopy. If they have done these tests, follow a high fiber diet. Watch what your are eating. Make sure you are going. You know what I mean. If you keep having severe pain, keep bugging your doctor. If he diagnoses you with irritable bile syndrome, good luck. Stress and lack of fiber brings it on. A good walk is great, too. They can do ultrasound on your stomach, but they usually need a good cause. They did it once to me. I think they do that for kidney stones and gall bladder problems. I was o.k.
I live with pain, especially on my left side. But I need to have tests, as often as the doctor prescribes. They can save your life. But don't worry so much. Everything isn't always the worse. We live in stressful times, unhealthy eating habits, and lack of fiber diets. I don't have the money to eat as healthy as I should. But I try to eat healthy as I can afford. Stress is the killer of man. I don't think I should take medicine for the rest of my life. But until I stop hurting, it is all I know to do. Good luck!