If I understand correctly, you have a pain in the heart area, you don’t really know why (physically).
You think the pain is caused by a demon attack, because you have abilities?
What do you mean the main dude within is shiva? Within what?
What other symptoms do you experience other than heart ache?
Have you considered going to the doctor, to make sure there is no blood clot or whatever? I have no idea what level of pain you’re experiencing…