Need Advice!!!

So I'm 17 years old and I've been sexually active since I was 15. No one ever talked to me about birth control until I met my current boyfriend who is also 17. And I finally decided I was going to get on it. So I went to the health department on 11/21 and they did my exam and prescribed me the pill I decided to try. They told me to start taking it the Sunday after I start my period which I will start it this coming Sunday 12/4. But after school today I got a call from them saying one of my test came back positive for chlamydia and they told me to come in on tuesday 12/6. I'm super depressed and upset and I need advice of what to do. Do I need to tell my previous partners? And any advice that would really help me out. Thank you.