Women can carry chlamydia for many months and maybe sometimes for a few years. Some doctors and clinics test women regularly for chlamydia, others don't, depending on the woman's age and sexual history. Your gf might have been tested regularly but not been infected until recently. You'll have to ask her.
Your PCP is a good start; you can always ask her if referral to a urologist is necessary.
Welcome to the forum. I'll try to help with these interesting questions.
Chlamydia probably can persist for years, but it is rare, especially in men. To my knowledge, the longest infection ever documented in the medical literature is 4 years, in a woman. The treatment you received 4 years ago was azithromycin, which is at least 95% reliable. So for you to have had chlamydia that long would mean 2 very unlikely events (unusually prolonged infection plus treatment failure) -- and the odds of both these things happening are very, very low. However, I cannot say there is no chance of it.
I don't know your girlfriend and cannot predict whether it is likely she has had other partners. However, from a purely statistical standpoint, option 6 -- that you have a new infection from your girlfriend -- is the most likely explanation. The large majority of new chlamydial infections in outwardly monogamous couples occur because one partner has had sex with other partners.
Another possibility, which you don't mention, is that your test result is wrong. This is unlikely with modern chlamydia tests. But if you had an older kind of test, it might be possible. If your doctor's office can tell you exactly what test was done, I can comment further about it.
Those comments answer questions 1, 4 and 6. Questions 2, 3 and 5: Chlamydia rarely causes bloody semen, so this might be an entirely separate problem. Occasional blood in semen is fairly common in men, sometimes without apparent cause. Other times it results from trauma, e.g. from bicycling, horseback riding, trail biking, etc. (I've had it myself, after a long bike ride.) It generally clears up on its own. Whether due to chlamydia or not, it probably does not indicate any serious genital tract damage and infertility isn't at all likely. However, you should keep the doctor's appointment (with a urologist?) then follow that provider's advice.
Whether or not your girlfriend acknowledges other sex partners, she needs to be tested for chlamydia and should be treated for it, even if her own test is negative.
In summary: Your chlamydial infection probably is recent; probably isn't serious; and might have nothing to do with the bloody semen. You'll need to discuss the situation with your girlfriend and make sure she gets tested and treated.
Good luck-- HHH, MD
Thank you for your speedy help. Two things: 1) Don't women get tested for these things at their yearly OBGYN? So how come it hasn't come up with her in all these years if I past it to her. So I guess my question is how long (reasonably) could Chlamydia lay dormant?
2) I didn't see a specialist just my PCP. I am going to see her in 2 weeks to follow up. Should I get a second look at that bloody seaman from a specialist? It has been occurring for over a month.