Wow - sounds like a difficult period for you guys! My suggestion (after raising two girls to the still tender ages of almost 3+5) would be to call her pediatrician and either talk to the nurse or also make an appointment (eps. if the nurse cannot answer the question to your satisfaction or recommends a visit). I've gotten through a lot of behavior changes/challenges this way - the nurses are often very helpful in situations like this - they've seen so much. Also, the Dr might just want to check her out to make sure it's not something you can't readily diagnose.
And then you should get yourself to an orthopedist about your knee (if you haven't already)! You don't want to risk another fall if your knee is not healed right - an orthopedist will also be able to get you therapy and advice. (this is just from the personal experience of limping around with what I thought was a twisted ankle for a month before seeing a Dr and finding out it was much more - stubborn me!)
The best of luck with your daughter, your pregnancy and your knee! You'll get through it, but it is a lot all at once.