Daily headaches since heart stent

I'm 53 yr old female. July '08 had catheterization with stent placement.  Cardiologist prescribed 75mg plavix, 325 mg aspirin, and 40mg simvastatin (zocor).  Three days after the stent placement, I started with the chest pains again.  Dr ordered 30mg isosorbide which gave me headaches everyday but no more chest pains.  After 5 weeks my cardiologist said to cut them in half which I did and after 2 weeks I'm still getting the headaches and now mild chest pains again.   Has anyone else had this problem?  The weird thing is, I tried stopping the isosorbide for 2 days and still got the headaches and worse chest pain.  Today I resumed the 1/2 med and severe headache ensued.  I called my cardiologist several days ago to see if we could try something else but my call has not been returned.  Anyone have any help or advise?