I dislocated my shoulder on a fall a week ago and the hospital said the xrays were good, but everytime i sneeze, my shoulder pops in and out?

Need Ortho followup: X-ray only shows that you did not damage the bones. Dislocation often causes ligament injuries, and if continuing to pop in/out, then will likely need surgery to tighten to improve function and reduce reinjury / ongoing injury. See an orthopedic surgeon who specializes in shoulder work for an evaluation.

Orthopedic surgeon: I would see an orthopedic surgeon and let them see if they think that you need an mri.