In order to change her custom designed meds, doctors had to carefully wean her from the current ones. Not doing so could cause her to become suicidal. Yes, her situation is that serious.
Once Britney was cleared of her previous prescription regime, a new one had to be created by trial and error, and those errors made her unstable and unwilling to cooperate with the medical team working with her. This is when she was admitted to a mental healthcare facility.
Again, best wishes to Britney and her father for good health, and their family.