It sounds like you have some rectal bleeding
when you use the bathroom. You should make an appointment with your primary care doctor
. Rectal bleeding can be caused by a number of different disease processes. Your gastric bypass could also play a role in it though it is not clear whether it is causing your rectal bleeding now. Rectal bleeding can be caused by an upper gastrointestinal bleeding from peptic ulcer disease. It is usually associated with abdominal pain and dark stool though you can have bright red blood if the bleeding is profuse. Another possibility is a lower gastrointestinal bleed such as diverticulosis, which causes painless bleeding. It is associated with bright red blood. Another possibility is hemorrhoids
which can be painful or painless. External hemorrhoids are painful and located on the skin outside the anus. Internal hemorrhoids are internal and are painless. These conditions are worsened with constipation. Another possibility is ischemic colon disease where a part of the colon is not getting enough blood. It is usually associated with abdominal pain with eating foods and blood in the stool. Again, you should make an appointment with your primary care doctor to figure out the exact cause. They will do lab tests and a guaic test. If you have symptoms of dizziness, shortness of breath, or profuse bleeding, you should go to your emergency room.