Hello Doctor. About four months ago, I received unprotected oral sex from a  41 year white woman other than my girlfriend for about 3 minutes.  I went about 15 days without symptoms, but I panicked because I read men can not have symptoms. At the time I was taking doxy for foot infection.  Anyways, I went to my doctor, and he collected a urine sample.   I was having  a severe panic attack to where I could not breath worried about an infection or HIV. He said I should be okay.  Feeling bad for me I guess he gave me an injection and 1g tablets. A few days later my urine test was negative.

I continued relations back with my partner a week later after she returned from her vacation. All was good.   Two months ago, she complained of severe back pain,   could not walk, severe pain in her stomach and vagina.  We ran to the hospital. She had blood in her urine and the doctor said she had a few kidney stones. They also performed a CT scan of her  pelvis.  Everything was negative. Last week she was complaining  a little irritation when she peed. She was given some medicine for a UTI.

Looking online I read about PID.  They seem similar but different to some of these issues .

My questions are :

Is it possible my actions could have caused this issue to my partner? 

Are my negative  test results and treatment reliable?

What were my chances of catching something  1 out 10, 1 out of 1,000?

What would PID look like if it was my fault? What would be the incubation period?

Would a CT scan identify PID?

Should I re-test?

Guilt is killing me more at this point.

Welcome to our Forum. I'll be glad to comment.  Your partner's problems do not sound like PID but are more consistent with either a urinary track infection or kidney stones, neither of which would be an STI.  The exposure you describe four months ago was low risk-  most people do not have STIs, particularly oral STIs which can be transmitted through oral sex and few STIs are acquired due to receipt of oral sex- there are no cases of HIV documented to oral resulting from oral sex.  The major infections which might occur due to oral sex are gonorrhea or non-gonococcal urethritis due to bacteria other than chlamydia (chlamydia infections from oral sex are very, very rare) and although some such infections may be asymptomatic, most cause symptoms.  Further, in your case if you were taking doxycycline during your time of exposure, this is likely to have prevented acquisition of STI as well.  Having said this., let me now answer your specific questions:

Is it possible my actions could have caused this issue to my partner? 

See above, there is virtually no chance that your actions have led to your partners recent problems.

Are my negative  test results and treatment reliable?

Yes, the tests were reliable. Similarly, your treatment which sounds as though it was an injection of ceftriaxone and azithromycin pills is recommended therapy for gonorrhea, chlamydia and NGU.  thus in the most unlikely event that you had one of these, the treatment would have cured it.

What were my chances of catching something  1 out 10, 1 out of 1,000?

Overall, estimates are difficult to come up with.  Given the specifics, in the neighborhood of 1 in 1000 or less.  Not something to be worried about.

What would PID look like if it was my fault? What would be the incubation period?

This does not look or sound like PID/  Do not worry about it.

Would a CT scan identify PID?

Yes, a CT would provide evidence of PID.

Should I re-test?

Re-testing is a waste of time and money.

I hope these comments are helpful to you. EWH