The average processing time in Pretoria for spousal PR applications is anywhere from 4 to 12 months. http://www.cic.gc.ca/english/information/times/international/05-fc-spouses.asp#africa
What do you mean by saying that your medical is under review? Are they asking you to re-do any tests? If so, you can probably expect your case processing time to be in the upper end of that range, but it's really hard to say without more information. Good luck.
EDIT: Just to clarify: those times are once your application actually reaches SA. When you said that your case started at the end of August, I wasn't sure if you meant that is when you submitted it to Mississauga CPC or that is when your case started processing in South Africa.