Is my nursing agency cheating me from medicaid payments?

I've worked with an agency in Virginia for almost a year and for apast 10 months, i have been with the same clients and really love and care about them. I have been getting the same rate, which is $23.00/hr for one client and $32.00/hr for a brother and sister ( my agency called it congregate billing). I work about 70 hours a week, and i had been sick so i was not able to turn in previous hours worked. Last Friday I went in to turn my hours, and i had a combined total of about 320 hours. When i went in they tried to hand me a paper for me to sign. They said since August that they had made pay cuts and that my $32.00/hr was going to be cut down to $25.00 because there was another nurse that was working with 3 kids and she was getting paid $25.00/hr. They also said that my $23.00/hr is going to be cut down to $21.00 because my client is not a vent case. I told them thanks for telling me and asked when they were going to start the change. The thing that made me upset is that they said they were going to apply those changes to my 320 hours I already worked. I told them it was unfair, because they had never told me that I was getting a paycut, and that I have rent, and school fees to pay. I really love and care about my clients and their families, but I do not think my agency is being fair. Also they have this rule now that time sheets after 30 days wont be paid, and they did that with 48hours i had worked before. i was very sad about that and felt its because I am so much younger. I know for a fact they are billing medicaid and I am not getting paid. Please help me!! I love my cases and I want to stay with my clients but is my agency legally or morally right?