Hi Buffalogal. Sorry for your difficult time.
And I know how it feels hurtful when our children pull away. But from what you've said, it seems to me that maybe your daughter could simply be feeling overwhelmed and doing a bit of normal mini-rebellion to have a bit of space and feel that she's claiming her own life. Natural phases of growing up.
And even though it's understandable that you required her to dispense your meds in the situation, perhaps it's also understandable that she may feel some resentment about having to be in a caring role for her mother. It's good you have your sister to help with that at this time.
I hope things are improving for you