8/25/13 blood pressure ranged from 112/66 to 90/64 and today 8/26/13 it's ranged from 126/53 to 106/62 to 130/50 I have been really weak and had dark stools for today. Have had bleeding ulcer in the past. Should I go to the ER?

Or make an appointment with your regular doctor as soon as you can. You might get more exhaustive tests with your regular doctor.

You should call your doctor's office and even if they are closed, leave a message saying what you said here (no need to state all the BPs).

You just don't get the most comprehensive care you need for something like this in the ER.