I wanted to know if I had phimosis ... What to do?

Hello, I wanted to know if I have phimosis. I am 18 years old and a virgin, but one day in the bath can expose my glans and it hurt, with that it increased the size of the ring of the foreskin and the glans was more exposed. But after that I can not but expose the whole glans, only a little more than half. And if I try to expose totally hurt. What should I do?