My Daughter Is Complaining Of Knee Pain And Neck Pain

My daughter is complaining of knee pain and neck pain when she moves certain ways. The other day, we were playing and doing squatting type moves and as she attempted, she began to laugh a painful laugh and complain that it "hurt really bad". Her knees and legs were trembling and she was no in a full squat position. She is 6 years old and has been diagnosed with sensory integration disorder/ autism spectrum. She typically does not complain of pain even when she should be in pain (bumping her head, for example) or is slow to respond to the pain.