my cousin had this problem last week. her BP was high, they got the BP down with medication and her heart is looking better (less enlarged). I understand wanting to do things naturally, I hate taking anything too, but I think for something like this you need to find out what is causing the pains and enlargment and get that under control first and foremost, likely with medication. After that I'm sure you can work with doctors to find out what sort of lifestyle changes you can make to help your situation.
If it is high blood pressure causing these problems and you need meds, TAKE THEM. My cousin stopped taking hers and not only is her heart enlarged but now her kidneys aren't functioning either. Had she kept taking the meds this wouldn't have happened. :-( I hope you are well soon!
There is something that caused the enlarged heart, it would be helpful to know if you have high blood pressure (one possible cause).
If there is some ongoing force (e.g., high BP) it has to be stopped/treated.
I have not none-RX ideas other than to look on for the "healthy heart' stuff here and elsewhere on the web.
I did find this on our family of Communities.
http://www.medhelp.org/posts/show/406447