Respite Home Missed My Disabled Son's Seizure Medication - What Are My Options?

Texas - My son (19) has autism, intellectual disability and epilepsy. He stayed at a respite home from Friday 6pm until Sunday 12pm. At 3:45pm Sunday, he had a severe grand mal seizure - much worse than any in recent months. The seizure lasted about 2 minutes, with him coming in and out of consciousness, and he bit his tongue.

He's prescribed Lacosamide for seizures. When I called the respite home, the afternoon staff member (different from morning staff) told me there was no initial next to the morning medication spot, suggesting his dose was missed.

This seems like serious negligence that put my son at risk. What steps should I take to address this? Should I file a formal complaint? Document everything? Contact a lawyer?