Suggest An Alternative To Magnesium

History - My Mother has Parkinson's symptoms, refuses to take Parkinson's medicine, is allergic to Sulfa, and has a long history of UTI which did not go away after trying several different antibiotics. She is in fair physical health (with the exception of the Parkinson's) and is in great mental and cognitive health. Typically mom refuses antibiotics because they don't make the UTI go away but she did try again last June-July with several different ones to no avail. Mom takes a lot of supplements. The Nephrologist was only concerned with the Potassium (which she doesn't take any more) and the Magnesium (which because her levels were looking normal again, she is taking them again to help with BM regularity. Now - Mother broke her femur in 3 places just after Christmas and is in rehab but the doctors have been concerned with her kidney performance. Her creatinine and potassium are at the high range of normal (2.4 / 4.9) but they fluctuate a lot. Just before her surgery both her creatinine and potassium were very high and they said her kidneys were at 10% functioning. The numbers have since gone down but still fluctuate (it seems with maybe the diet). She has also refused diuretics. She was impacted last week and they gave her Kionex which made her feel very bad for a while until she finally had a loose BM. She takes Magnesium (every AM and M, W, F PMs) . I'm wondering what can Mom take other than Magnesium that will be effective and not cause an allergic reaction (Sulfa).