if you are doing a lot of running which means you will be losing fat..your legs will get smaller not bigger..cooling down just gradually slow to a walk then do some stretching
were they big before you ran..are you looking in the mirror or looking down at your thighs..if you have lost fat and gained some muscle they might look bigger but i doubt if they are.
Be sure to stretch properly before AND after you run.. I for one tend to bulk up if I do not stretch properly, also it will keep you from injuring yourself and it feels oh so good
If its after ur run that ur thighs are bigger, it's because you have been exercising which is pumping more blood around ur body making the muscle look bigger, but in a few hours, its back to normal.
Take some measurements. If possible have SOMEONE else take the measurements. They may be getting bigger. I don't know. I know a little about you though and I feel pretty comfortable saying that your thighs are okay
Just focus on eating 5-6 times per day. Focus on doing a mix of good cardio and weight training too. Continue to focus on health and not numbers or appearance... as hard as that may sound.