I have been told that i have A.F.?

i have just been discharged from hospital after 3 weeks i was in the cardiac unit and was told that i have A.F. i have been on tablets to bring down my heart rate and i am now on warfarin,I have to go back to hospital at a later date to have a cardioversion.In the meantime i still get a dull ache on the left hand side of my chest is this because i have an irregular heartbeat and will it go away after treatment thank you mike.