You should def go in and get checked out. Blood clot was my first thought.
Swelling should go down after giving birth I know it did for me.. When I was pregnant with my first I had pretty bad swelling on justoneleg and they were worried it was a blood clot which can be very dangerous.. Definitely go in and have it checked out..
You should probably go to urgent care or the er it could be dehydration or something worse its better to be safe than sorry!!
If its just one leg i would call the dr...it could be several thing causing it!