How would I know if I had Parkinson's or Huntington's? I have a family history of both?

And is it possible to have both conditions? My paternal great grandmother had Huntington's and my great grandfather had Parkinson's. As far as I know, there aren't any sufferers in my close family. But the majority of my close family are middle aged or younger. I don't think any of them had genetic testing. Not too sure how likely it is that I have either one of those, but in the recent years I've been suffering from symptoms which overlap between the two, BUT also could be attributed to entirely different illnesses.