Rhonda's given you links to good information about this. I think generally it is much more rare than the cancers you already know about. But for your own peace of mind, you might want to start a small log -- record the symptoms you're now experiencing, and see if they worsen, or go away in time, or if there are new things going on. And then if they don't dissipate, call the doctor, remind her of your visit, and tell her what has been going on.
Unfortunately there are lots of disorders that can mimic MS, including things as benign as pre-menopause. Your sister was 48; how old are you? Is pre-menopause a possibility? It can start to cause problems in women as young as in their 30's, and last through the early 50's. If your symptoms persist, you might want to go back to the doctor and be tested for this, as well as things like thyroid problems, or diabetes, which also can cause some of those kinds of symptoms.
I'm very sorry for the loss of your sister. Losing a sibling is very hard, I know. Take care.
...I am not a doctor, nor health professional, and don't pretend to be one, here.....