My reputation wass 30 but now it's 21 - Help !!!!!!

My reputation was 30 and just now I opened up my account it's 21.. What's going on? Did someone flag me? Is it becausse I upvoted my posts? I am new here guys please teach me the rules first... Why id my Reputation gone now ?

Some one please help !!! I've made quality posts till now.. Can someone help me get the reputation back or solve this issue??