Hi Cindy,
Yes, contact your GP. Anytime you change your medication, you should notify you MD and especially so with the symptoms you are experiencing.
Hypotension or low blood pressure is typically when blood pressure drops to 90/60 or below. However, with previous heart issues you may have symptoms of low blood pressure at 100/60. The most common symptoms for low blood pressure are lightheadedness (which you are experiencing) and fatigue. I'm not sure where your stomach pains fall into the mix.
Contact your MD to determine the next best step.
All the best,
Lisa Nelson, RD, LN
The Heart of Health ezine and free report