Viagra + 14 year old?

Ok so I'm at my cousin's house & he tricked me into taking Viagra. It was my uncle's. I have a cold right now & he told me it was generic Advil. But he just told me 45 min later that it was joke & he feels bad. I AM FREAKING OUT! I researched what could happen. What should I do?! I also read to just masturbate. PLEASE HELP ME!