Is it harmful to the arm and/or circulation to take blood pressure too often? took it 50 times a day for past 2 days, and now my arm feels sore.

Reduce #BP readings: Unclear why you are taking BP, but I would recommend taking blood pressure no more than a few times/day! Checking too often can cause stress and this can result in high readings. When BP is taken, the cuff is inflated to a pressure that prevents blood flow through the artery. This pressure can cause temporary pain and tingling, and this would be worse if taking an excessive number BP measurements.