Slow pulse symptoms and conditions

I just started taking Toprol XL 50 mg about a week ago. I feel a little confused though on the doctor's judgment. I have a slow pulse (tends to run in the forties) from running a few miles a day and have mild hypotension. I was dizzy, lightheaded, fainted a few times, blurred vision, shortness of breath, chest palpitations and chest pain. My pulse would go from 35 to 170 just by standing and walking ten feet. The doctors determined I have what is known as POTS Disease, even though i suffered some of these symptoms lying down. Although the Toprol is helping with my palpitations and chest pain, it makes my resting heart rate and blood pressure even slower. Doesn't that seem dangerous, seeing as it's already low for even an athlete? My symptoms seem to be remaining the same besides that (which I guess is good seeing as Toprol can cause my symptoms, therefore I thought my dizziness, etc. may get worse). It's causing trouble sleeping, vomiting, cold feet and fingers.

Have any females suffered from decreased sexual desire with this med? I have had the cough, weakness, dizziness, sore throat, runny nose, numbness and tingling in my hands, weakness in lifting with my arms, coughing, and catch my breath a lot. I thought it was just "getting used to the med". I am convinced this is a dangerous med, I am off it for good.