Amen to Chris' response. If your meds are not working, ya gotta try something else! If you really have PD,, and you are NOT taking any form of Levodopa, I think you should find another doc., preferably a movement disorder specialist. I would guess that you have been prescribed some sort of dopamine agonist. Those may help for a while, but after 4+ years, it's time to try something else.
Good luck!
Jim Gilmore