HI.I am 22 , I have been fair and had a very good white skin but now my skin is darker,why it has happened?

I am student,6th semster of biology,my skin was famouse as best skin in my family,but now its 2-3 years its darker and not as fresh as it used to be.i don`t use any special lotion or cream either,but for a span like 1 year, i used a herbal antiUV cream, but no more after i felt my skin is becomin darker(idon`t know if its because of that or not) how ever its more than one year i don`t even use that.I am a fruit fan ,eat lots of fruit.but still same...my skin is darker and has not returned to its past, am sad about it , and wanna know why it has happened ?