5 month old cries hysterically in sleep

My baby girl has a dr appt next month and I will bring up with doctor but I’m wondering have any other parents dealt with their baby randomly burst into loud hysterically cries & keep their eyes shut? She first started doing this at home bu now she no longer does it at home just when she’s at other family members house. My mother & Grandmother (those are the only places she goes other than with me). She will be in a deep, still sleep and start screaming but doesn’t necessarily wake up. There’s normally tears on her face and coming from her closed eyes. I’m wondering if she’s having some type of nightmare or could something else be going on...