How can I get the authority to get my Mom into a facility when the time comes with out her permission?

My mother fell and dislocated her shoulder about 3 yrs ago. Then she a heart attack and they gave her a shunt a year after that. All the while her memory seemed "Off". She moved out of the house she was in, and moved in with me and my husband for 6 months. She was just as difficult to live with as ever. Her reasoning abilities seemed to me to me going down hill, but she was still very aware of all that was going on, and still able to make her own decisions, but since my granddad, her father, died of alzheimers, I knew there were signs. She moved out into her own apartment about 25 minutes away, because my brother didn't have a home to go to, and she didn't want to live alone. So for the last 2 years she, my brother, and his girlfriend and their 4 yr old have been living with my Mom. I take care of all her doctors visits and recently, after she had another heart attack in Oct. of 2012, I got POA because her mind has gotten way worse. Over the last 6 months, she has come to the point that she can't do simple things like, remember how she is helped out of her chair ( her knees are bad too) to not remembering that she hasn't washed herself. I have been over and made her let me shower her, but she is a big woman and is very combative and doesn't want help, but complains about everything she does, that it "hurts". Sometimes I think some of it is put on. She is a large woman, and there is coming a time very soon that we aren't going to be able to help her. The doctor ordered home health and they are suppose to call and set something up. We do not have money to help my Mom. She only has Medicare and a fixed income. She has always said, she "doesn't want to go to a nursing home" yet, she putting a lot of responsibility on all her loved ones and has always been a selfish person, and I kind of feel like some of this is for attention. I don't know how to talk to her , because I don't know when it is put on, and when she is really in a "fog". How can I get the authority to have her transferred toa facility with out having to have her permission. I don't have the money for a lawyer and I don't know how much longer we can help her, physically. This very stressfull and I don't know what to do. Any suggestions? Thank you!