What Causes Bright Red Blotches On Neck And Face When Under Stress?

I have times thru out most days, with sudden onset of bright red splotches on neck and sometimes face. Mos of the time it is after I have had anxiety or stress at a situation. But it comes on quick during the situation and goes away usaully in a few hours. Is it blood pressure related. My blood pressure is usually 130's or 70's.

I have also been told I have Ulcerated Colitis or Chrones.