Here, you have not mention clearly which tablet you have started ? I need to know that to explain the resion of
back pain with fast heart beat. How ever it may or may not be related to it. I suggest to check with your doctor on it.
Now suppose if it is not related to it then check on your back pain is it at your back only or it radiates from your back to your legs. Here you have mention only back pain. So many times it is related to
muscular pain due to weakness of back muscles or over strain pain in back.
You can use hot pack at home and do good spinal exercise with suggestion of specialist to strengthen your back and improve back muscle stamina.
To check on heart, check that do you get this heart pain along with breathing difficulty ? and how often it happens? Here you have mention only heart beats become fast. It can also be due to
anxiety. So do
yoga, pranayama regularly and take proper sleep also.
Many times just because pain in body also heart beat becomes more so it can be inter related too.
As per your question i have suggested you couple of things here in general.
specific suggestion is not possible since there is lack of information from your end on past medical history for heart, back, acidity problem as well tablet for what it is? And which tablet it is?
I suggest to keep your question again with proper information if this is not useful.
Take care.