My left labia minora has recently gotten larger...

Hey everybody. I'm 19 and have been sexually active for two years. Recently, like months ago, my left labia minora has gotten larger than the right that it hangs out... also along its rim, it got a little darker than normal. Sometimes it irritates me. Could I have simply been worn out and stretched? If not, then what else could've caused it? And what do I do to make it return to its normal size? How do I stop the right one from ending up the same way too? Any help would be appreciated. Thank you.