fighting to get meds

I have been battling cancer for the last 4 years and not doing too bad but I am now fighting the hospital to get the magnesium as they say it is too expensive and will not be having it, my problem is I have tried others but as I have an Ileostomy the other one makes it too thin and I lose too much fluid, this has really dragged me down over the last week and find my self now wanting to give up