I was babysitting my grandson when he was about that age. I spent most of the time on the floor with him when he wasn't sleeping. He was a good baby and easy to please. If he wanted to be held, he crawled then toddled over to me. I kept his toy box next to me so he wouldn't wander off. He crawled faster than I did.
As ususal, Lee gave you good advice. Since you are having a nerve conduction study next week, do not babysit that day. As a matter of fact, don't do it the next day. You may be a bit sore if the test is extensive and it sounds like it might be. Get some rest.
Try a nice strong cup of catnip tea at bedtime. Use two bags per cup of tea and let it steep at least 15 minutes. I found it to be a good mucscle relaxer and sleep aid. Catnip is in the mint family and is rather tasty. I also flavor it sometimes by breaking open a cranberry capsule and dumping in the contents. Sweeten with honey or whatever you like. That makes a tasty drink. Hang in there.