Hi Krissy, thanks for your question!
So lets break this down a little bit. You were recently hospitalized for pelvic inflammatory disease which is most often caused by either Chlamydia or Gonorrhea but can also happen post-abortion or miscarriage and can also be related to having an IUD. Your doctors clearly feel that yours was caused by Chlamydia. Chlamydia is a tricky infection because you can have it for a while and still show little or no symptoms (especially for women, who often show no symptoms even for months), therefore causing it to go unnoticed and untreated. Symptoms are more prominent in men though (i.e. discharge from the penis, pain during urination) and are therefore harder to ignore. With this information alone it would seem possible that you had Chlamydia before you started having sex with your current boyfriend in March. However, you say that you had an STD test in June and it came back negative. So, false negative tests. Although it is possible that you received a ‘false negative’ on your June test, it is very rare and unlikely. FYI, false positive tests are just as possible as false negatives. It is also possible that by June he had not yet transmitted the infection to you. He may have had it, but you did not yet. Or you were just recently infected and the infection was not yet strong enough to return the test positive. Were you still using condoms at that time? When was his last STD test and how did that go? If you were having unprotected sex between March and June then the chances of him having Chlamydia and you not is very slim.
Regardless of who had it first or who got it when and how, you both need to be treated and you should begin practicing safe sex again (in fact, it is recommended that you use condoms for the first 6 months of any new sexual relationship). It might also be a good idea now to get tested and visit the doctor regularly. You should keep consulting your doctors and take what they say seriously.
In my opinion, what this comes down to now is trust. Ask yourself these questions: do you trust him? Even if he did cheat on you and lie about it, do you still want to be with him and try to work it out or is that a deal breaker for you? What if it happens again? Will you be able to trust him now, or will this situation always be hanging over your heads causing doubt and conflict? Relationships are built on trust, and if you’ve now lost the trust you had in him then it is going to take a lot of work to gain that back. You know in your heart if he is someone that you want to work this out with or not.
Be safe and healthy and good luck!
Hillary for Alterheros