numbness in arm and fast heart beat

I am 28 years old and I have narcolepsy. I take ritalin. I was in a car accident a few years ago and I have had shoulder pain ever since. Recently, I have started having numbness in my left arm. I also have a fast hear beat at times due to the ritalin. Doc doesn't seem to acknowledge me when I ask if the 2 could be related. I am worried that i take ritalin and it causes problems and then I take pain meds to mask problems. Please help!