Caring for a Grasshopper?

We have a big garden full of these beautiful lubbers which I really love and adore. However, we recently had our landscaper cut a bush and the next day to my horror I found, on what was left of the bush, a sweet little nymph lubber with a humongous abscess on it, coming from his back, area connected to the head (but abscess not connected to his head). I don't know exactly what it is or where it's from or what I can do to help him. But any information at all would be helpful.

Currently I am housing him inside, in an open airy box full of the leaves that he likes and some water. He is hardly moving but having body/muscle spasms and obviously very weak he can hardly stand/move around.

Please let me know if you have any ideas or direction :(

By Cam