Hi. Im 15, i get those types of pains all the time. Either it's a nerve i've sat on in the night or i have agonising growth pains, it feels like my bones are being ripped out. Come 20-25 years old, the pains will have gone, it's nothing at all serious and doesn't need a doctor unless the pain or numbness gets unbearable. Just rest your leg straight and relax when ever it comes.
hold everything... dont get too excited. your 16 and have growing pains. be patient i'm 79 and when i was your age i thought i had something wrong with my lungs.i was overly concious of my breathing. it's laughable now, when your my age you'll give marvelous advice just like i did !! ps: be kind to yourself and forgive yourself easily. also be kind to others and have a good life.
You could be laying on a nerve whilst sleeping,go and see a doctor about this,but in the mean time when this pain do happen always keep it straight and put pillows under it to ease the pain.
Sounds awful! See a doctor soon!!