Do i have an STD? please help!?

I am 13 and had for the first time a few days ago. I am usually just paranoid and the only symptoms i have had are yellowish discharge, pain in the , and the first like day after i had small purple/grey blotches on my lower stomache but they are gone now. If this was an STD which one would it be? And i want to be tested without my parents knowing, so how would i do that? You have to be 14 to get tested without your parents knowing so i dont know what to do. Help!