@apoind1 it sounds like you have low blood pressure like me. There are things you can try: the pen for Tymlos has clicks that measure the dose. Each click is 10mcg. Try going to a half dose, 4 clicks or 40mcg.

I bought a blood pressure cuff and checked my blood pressure prior to injecting and if low, I hydrated and ate salty things and waited a bit before injection, checking blood pressure all the while.

You will of course talk to your doctor but those exertions would maybe lower my blood pressure further. That would explain fast heart beat or feeling faint but the pain rising from base of spine is something your doctor would have to explain.