How to deal with a 4 yr old that has totally turned for the worst?

My 4 year old is like a different person from whom i gave birth too. She was the best behaived child i new and anyone else knew, now it is like WHAT WENT WRONG???? We fight every morning getting ready for school, wether it is about her clothes,shoes,brushing her hair or her teeth. It is always something. We both end up in tears and that makes for a bad day. After i get her and i settled down she is fine. Her teacher's love her and can not believe we are having these problems. They say she is perfect at school and has great manners. My husband is going threw some medical issues due to failing kidney's and is having to be on dialysis 3 days a week but is still able to do everything he did before, I dont no if she is senseing something there or what. Her and her dad are closer now then ever. I just need some new idea's on what to do. I think i have tried everything....