Please help me sumone/anyone...?

Hello Everyone, I know this site is not a place for advice but I am beyond frustrated. It all started with mild rectal bleeding every now and then (off and on 10 yrs), indigestion symptoms, fatigue, tachycardia, (fast heart rate) passing gas and now pain on the left side of my stomach and side (rib cage area). I went to the dr who said all labs are normal. I had a digital rectal exam, and an anascopy all which were negative. I also had a colonoscopy 10 yrs ago when the bleeding first began that too was negative. I am so petrified that I may have colon cancer. I have heard so many stories about mis diagnosis and it's driving me crazy. I am 40yrs old and never had any health problems. I did have a full cardiac workup due to the tachycardia and no underlying cause was found they just gave me propranolol to take once a day to slow my heart rate. I am going back to the dr. next week and I am going to insist he refer me to a gastro dr. If anyone has any advice or knowledge please don't hesitate to reply. Thank You.