A couple of things: have the MTS checked out. It can be manifested in the right leg, although it is more common in the left; and, make sure you don't have a low grade infection somewhere. I've found that if I have a low grade infection, ie, a kidney infection (very mild), or a gall bladder difficulty, I'll get worse. When those are gone, I'm great again. It doesn't take much of an infection to do it, either
There's always a reason, it's just finding it so we can get it fixed
Becky and I wish so much for your quick recovery. Only the very best wishes to you, Katie, and your wee one.