I'm a little scared !! Any advice??

I'm 18 years old and I've been having sex with my first for the last year & a half . We never used condoms because he always pulled out . About 2 weeks ago he ejactulated inside of me " a little " so he says .. && unlike him I'm really worried .. Lately I can feel my body going thru changes.. As far bloating , back pains, and even the fighting of my stomach.