I would take her to the vet tomorrow to be checked over; at only eight months, her joints are far from fully formed and I would want to be absolutely certain that any damage was found quickly and allowed/assisted to heal properly. Without that, you could be storing up very serious, long term problems for the future.
Until you get there, I would restrict to lead wees and poos only; no walks, no games, no mucking about.
I have assumed she has retreated to her crate because she is in pain, not because she is tired.
My 8 month old lab pup twisted her left front shoulder when running about with my brother's dog today. She has been limping and has retreated to her crate and won't come out. Should i take her to the vet with this? Is it likely to get better by itself? I really don't know what i should do but she looks so sad.