L.R.
Please see your doctor IMMEDIATELY -- today -- do not wait. You may need to go to an ER. This may not be the "normal" leg cramps you had before. You may have DVT -- deep vein thrombosis, a blood clot in your legs, and if the clot moves through your bloodstream to your lungs, heart or brain it can be fatal. Sorry to sound scary, but women on birth control are at greater risk of DVT than other people. If you smoke -- you absolutely are at big risk of DVT since BC pills plus smoking is a huge, huge risk for clots. Even if you do not smoke, BC increases the risk. You just started a NEW medication and the pain started at the same time -- please don't ignore what your body's telling you: There may be a link.
Yes, this MAY be something else but if it's a clot or clots and you don't get it diagnosed immediately and are not given clot-busting drugs (and taken off this BC) -- you could be gravely hurt.
Your ob/gyn may not be very familiar with DVT. Get to the ER or a doctor today, don't wait. If you are reluctant to go because you've had other cramps in the past, or you "feel silly" if it's nothing -- Better to go and be told "You're fine" than to say "I don't want to bother a doctor" and find out too late that it was DVT. I say this as a relative of someone who died of DVT. It wasn't BC related in that case, but it is a silent killer that acts like a lot of other things from cramps to muscle pulls from exercise.
These links mention the link between BC and blood clots.
http://abcnews.go.com/GMA/story?id=5861083
http://www.livestrong.com/article/142607-a-blood-clot-leg...
http://www.mindbodygreen.com/0-6642/How-My-Birth-Control-...