Lower gastrointestinal bleeding: When to call
  Call 911 anytime you think you may need emergency care. For example, call if:
  - You have sudden, severe belly pain.
  - You vomit blood or what looks like coffee grounds.
  - You passed out (lost consciousness).
  - Your stools are maroon or very bloody.
  
  Call your doctor now or seek immediate medical care if:
  - You are dizzy or lightheaded, or you feel like you may faint.
  - Your stools are black and look like tar, or they have streaks of blood.
  - You have belly pain.
  - You vomit or have nausea.
  
 Watch closely for changes in your health, and be sure to contact your doctor if you do not get better as expected.