I hope you get some answers after your appt on Friday.
When I was first dx'd with MS, I too had urinary problems. I made several trips to the ER just to get "cathed" because I was not able to "pee." That was the beginning of my diagnosis process.
I had a bladder ultrasound, a CT scan, and was taught how to self-cath. The doc rx'd valium (5mg) for me when I am having problems so my bladder will relax enough to allow me to urinate. I really haven't had any serious problems except when I have an exacerbation.
I have had a lot of yeast infections in the past due to having so many IV solumedrol treatments. My ob/gyn doc finally suggested that I take daily AZO Yeast (over the counter) and it has been great. Not one yeast infection since. It's cheap stuff and I take 1 tablet daily.
Keep us posted on your appt on Friday and keep asking questions! We are here to help you.