There is a product called Bio Oil that you can find at any pharmacy or cosmetic section. I've used it on my thighs after hitting a growth spurt and getting taller, it works slowly but surely. Just follow the directions on the bottle and you will be on your way to stretch mark free skin. :)
To get rid of stretch marks, first assess the stretch marks before you select a treatment process. Consider getting a stretch mark treatment cream. Stretch marks are not going to disappear if you use a cream treatment, but they will soften and fade. Read more at http://www.ehow.com/how_2052796_get-rid-stretch-marks.html.
somtimes they are just a part of life whether its fom gaining or losing weight or for some other reason. everybody has them .our skin can be silly like that. you shouldnt worry tho. im sure you are a.o.k.