Hi, sorry to hear you’re going through this, how terrifying. It almost sounds like she’s having some sort of seizure. The clenched lips and blank stares. Seizure disorders can be very hard to diagnose. When this happens, does she lose control of her bladder? That often happens during a seizure. My daughter had a series of seizures in her early 20’s and it took probably 6 months of tests to come to really no conclusion at all. They put her on anti seizure meds for a couple years , weaned her off and no seizures since. Was told by specialists that seizures can happen randomly for no apparent reason.
However, the low oxygen levels sound more like s heart problem.
I’m not a doctor so just putting out some possibilities. I think I would have her see a neurologist to investigate possible seizures.
PS. In my daughters case, once she got to the ER after her seizures her EKG looked normal. They often rely on witness statements of what the seizure looked like when it was happening. They wanted to keep her overnight in the hospital and deprive her of sleep and monitor her because sleep deprivation can bring on a seizure. We opted not to do that and Thank God it resolved itself after 4 seizures in span of 3 years.
One last thought about the possibility of seizures- exposure to pesticides and other chemicals can also cause them. My daughters first seizure happened in a field while picking tomatoes. The doctors questioned the farm owner about what if any pesticides in he used on his crops, but he claimed he didn’t use any.
Best wishes to you and your mom and let us know if you find answers.