It pisses me off that I am letting my mom use my car.. Well she's has recently let my little sister take it and she…

It pisses me off that I am letting my mom use my car.. Well she's has recently let my little sister take it and she doesn't even bother to ask me.. Well today my sister asked me if I would take her to church for something that they are doing and I said yes well I called my daughters Doctor today because she's had diarrhea for about a month and it has gotten worse and they called me back and said that I needed to bring her in and so I made an appointment for today at 4:30 so I called my sister at 3 and told to she needed to head this way so I could take her to her church thing and go to the doctor and so I call her about 3:54 and she says I am about to be there so i told her that I wouldn't be able to take her to her church thing that I needed to go to the my daughter doctors appointment and she said "so just because she has diarrhea doesn't mean anything I get diarrhea that doesn't mean I am sick" and then she says that she'll just go to her church thing by herself.. Are you kidding me?? Like are you serious right now? So now it's a big deal that I want to take my daughter to the doctor... I didn't know I had to ask everyone in my family if it's okay to take her to the doctor...