What Causes Severe Nosebleeds From Left Nostril?

Since around 2003, I ve been having serious nosebleeds through my left nostril. After doing some research online back in about 2009-10, I took a flyer on my problem being linked to an H. Pylori infection in my system, and so I tried taking multiple capsules a day of sulforaphane, which much to my surprise, cured the problem for a couple of years. Unfortunately, the problem is back now worse than ever, and not even the sulforaphane is working. The problem has gotten so bad that not only might I start bleeding spontaneously at times, but always after I have a bowel movement. The blood quite literally streams out of my left nostril, and continues until I m able to blow mucous type blood out of the left nostril and my mouth, and then gradually, the bleeding begins to dry up. I m definitely frightened, suspecting I must have some intestinal type ulcer, but realizing it could be something even worse. I was hoping you could give me some insight, guidance and/or instructions on my problem and whom you think I should see for evaluation and treatment.