Considering moving 3 y/o to a new sitter...need advice!

Hi ladies! My daughter has gone to the same sitter for the last two years. Last year, my nephew (her best buddy) began going to the same sitter. This past winter, she began having some health problems (blood sugar, sleep apnea--she is in her mid 50s). She said she felt fine after a brief stint in her hospital, so even though I started to worry more, I left my daughter there. Over the last couple of months I feel like she has kind of "given up". She has been feeding the kids spaghetti and mashed potatoes (???) every day, and they are watching a lot of TV. She doesn't mistreat the kids...I'm just not as happy/comfortable as I used to be leaving my daughter there. My nephew is starting a part-time preschool program and my sister has found a sitter (someone I know and like) who is looking for kids to watch and will let her pay for the hours my nephew is there. One of the other girls the current sitter keeps is going to kindergarten, and the sitter's granddaughter will be starting part-time head start in a few weeks. Essentially, if I keep my daughter there she will be the only kid there most of the time. I am a teacher, and school starts back in a week and a half. This new sitter is a SAHM looking to make some extra money, and will not charge for school breaks or days my husband decides to keep our girl on his day off as long as we give her notice...so financially it will work out better for us. I am pretty sure I want to move my daughter to the new sitter as well (my sister has already spoken with her about meals, activity time--they go outside and play, which they never do at the current sitter). I'm just not sure how to go about it. We never signed any contracts or made any agreements about giving notice, but my conscience won't let me just stop taking her or canceling over the phone. I can afford to pay her a couple of weeks worth of pay , but am not sure if I should offer. I feel really bad about both of us (and the kiddo who is going to kindergarten) all leaving at the same time, but I feel like I am doing what is going to work best for my daughter/family. My husband just says he trusts my judgement, which isn't much help!