It's very interesting and a little scary that you mention that because, while I don't have any of the other warning signs, my grandfather recently passed away just short of the age of 80 from complications due to Parkinson's. For my own sanity I don't want to jump to any conclusions but I'll look into it, and I thank you for the suggestion. For what it's worth my voice has been relatively low and soft my whole life, so it's not a recent change or development. (I'm currently 27.)

In any case, talk to a doctor about it. Perhaps a speech and language therapist could help you.