Stretch marks

I recently developed red stretch marks on my thighs and I dont understand why. I THINK they are stretch marks but I have not had a major weight loss or gain recently but yet they still appeared. I do diving and right before I noticed them I landed really...

badly on my thighs. Could this be the result of that?

you are young, those stretch marks arent anything to worry about...so youre gettin a little thick in the thighs! most men love that, and almost everyone I know has always looked past any stretchmarks! society has ruined our self image! there is nothing wrong with the markings our body natuarly produces, society has taught us that they are ugly, and that imperfections should be bannished...and that everyone should be skinny and look like some sort of plastic doll! no matter what imperfections you have, whether it be dimples on your butt, stretchmarks on your thighs, or a period pimple on you chin, you are beautiful! if they bother you that much, get some cocoa butter! look for stuff for pregnant womens bellies! it works awesomely from what I hear!

just put some cream if you don't like it... it'll fade away, ... but keep in my mind it might take some time... ... and sometimes they might not go away, that's what I know...
and yes it might be cause of this landing on thighs...

Stretch marks are a normal part of puberty for most girls and guys. When a person grows or gains weight really quickly (like during puberty), that person may get fine lines on the body called stretch marks. Stretch marks happen when the skin is pulled by rapid growth or stretching. Although the skin is usually fairly elastic, when it's overstretched, the normal production of collagen (the major protein that makes up the connective tissue in your skin) is disrupted. As a result, scars called stretch marks may form.

Don't worry about it though, just keep on using a bio oil or cocoa butter to keep your skin supple and moisturized, that will also lighten them.

Source: http://kidshealth.org/teen/your_body/beautiful/stretch_marks.html#