My mother had breast cancer a year and half ago after that she became mentally unwell she was accusing my father of having an affair, she could smell gas in our home, she felt as tho people were following her when she was at home and out and About she used to follow people back who she tought we doing it to her. She seemed to link everything everyone said and came up crazy unablieveable scenarios. She was always angry and scared. She would stay at hotels instead of home. My sister and i got her help it was exteremly difficlut as she didnt think anything was wrong with her. She went to home with nurses there 24/7 for a week, she was also perscribed medication. She has been ok for a about 6 months and now she is starting it all over again. Only this time im alone with her :( i need support but i dont have anyone to help. Im scared myself to get dr's involved as i dont know what will happen, she has stopped her medication. And once again she has been thinking silly things such as people are coming into our home at night. Please help me with the next step??!

It must be very difficult.
Most important is that you actually get doctor's involved at the earliest. She may require to be hospitalized in a closed ward facility depending on what the doctor advises. From what you have said, she seems to be getting paranoid or even hallucinating. this requires urgent medication.

Medications should never be stopped unless the doctor (a qualified psychiatrist and not just any general practicioneer) says its ok

It will be difficult for you to manage her single handedly but if you can somehow get a family member, close relative or good friend/neighbour to stay at your home for a while or some during some parts of the day....you should be able to cope better

my prayers are for you. God Bless