i can sympathize with you. i have been dealing with depression most of my adult life. i believe it is also the first pd symptom that showed, phew, that was a bad time, about 8 years ago. dont give up on medication until you try all the different ones. lexipro was the last wonder and has been working for 5 years. i dred that it will quit working.
also, have you tried concerta? this drug has changed my life for the better.
you know, get out, be around people, do nice things for yourself, small steps of course, just one litle thing each day that you can do.