Heart problems can cause pain that one would never relate to the cardiac realm.
Deep muscle aches in the neck, back, shoulders can be symptoms.
There is no rhyme or reason to what can hurt or ache due to something going on with the heart.
I would suggest that the doctor look into this.
I am only saying this because I know first hand that heart attacks or problems can cause symptoms that would never, ever make one think of heart related problems at all.
Good luck,
Judy