I don't know what the weight of your bow is, but heavy bow value started dropping about 4 years ago. I use get a fair price for a heavy bow, 60 to 78#s, and sell it same day or a week. Now you can't hardly give on away and they can sit for months.
Might want to check out the Form Clock thread on the Shooters Form Forum and see if you can get your form in order, i.e, probably aligned and bone on structure. You shouldn't be putting stress on your shoulder when you shoot, and if your form promotes that, that lighter weight bow can do the same.
Best of Luck..... BTW, I just saw a beautiful pic of Hooker Valley, south island.