I read your question carefully and I understand your concern. Those symptoms seem compatible with a urinary tract infection. It is a very common complication in Multiple Sclerosis. It should be confirmed with a urine analysis, urine culture, complete blood count and perhaps and ultrasound of the kidneys since you refer pain in the right flank as well. Afterwards if bacterial infection is confirmed treatment with antibiotics will be necessary. I don t know what antibiotic you took, when and for how many days. Several antibiotics are available like ciprofloxacine, nitrofurantoine etc. I hope to have been of help.