hello. i woke up this morning with upper thigh pain. it is in the front of the thigh, right below my stomach. it gives me a lot of pain, and it is hard for me to walk normally. tonight, i noticed that there is actually some light swelling. no redness or a bruise, but if you touch both thighs you can feel the swell. is this something i can fix with exercise or stretching, or should i let it take its natural course? could it be something serious??