Try renting different lenses if there’s a rental service near you. You may also wish to try different more modern bodies that can handle higher ISOs with better quality across all ISOs. The D5100 can handle upto about 6400. But it starts to get a lot grainier at that setting. Given the low light… you’d need a longer exposure, too.
Apparently the admin of the group determines that my answer isn’t appropriate. So here is my full answer. Your camera is unlikely to be able to do what you want: it’s not exactly junk… but the issues you face in light and speed mean that this camera is probably, even with the best lenses, unable to capture what you need. Time to upgrade. I know: I have one.