Hey Cindy,
Weakness is not a good thing. I would definitely call your doctor. I am not thinking a cortisone shot will help but it is worth a try. You might want to ask for a script for physical therapy. If you are having some weakness, this is usually due to nerves not sending the right message - sometimes you can compensate by strengthening other muscles. I did this a bit after a really big, bad flare. I have this left knee that if I have all my weight on it, it will pop and I go crashing about. I have strengthened my leg muscles so that when that knee cuts loose I can catch myself. Talk to your doctor and see what he/she has to say about this.
I have a left leg that doesn't always follow the rules (mild foot drop and it is just generally clumsy) but I can easily stand up from a deep knee bend. I am not a skinny person - I am proud of how hard I have worked to get that leg strong.
Good luck with that. Please let us know how you are doing with this.