Welcome to the Forum.  I'll be pleased to comment.  Gonorrhea seems unlikely in this situation- the long interval between your exposure and the onset of symptoms, as well as the lack of obvious discharge from your penis are atypical for most gonorrhea.  Let me also caution you that your self medication (it is not clear to me if you have been self medicating or not) is never a good idea, nor is taking antibiotics without a clear diagnosis as many antibiotics lead to side effects which can be mistaken for other problems.

The risk for getting any STI from receipt of fellatio is quite small. The highest risks are for gonorrhea (over half of which would still be cured with Augmentin) or NGU.  In your case, the timing of your symptoms, weeks after your exposure and while taking Augmentin seems very unlikely.  A fungal infection would be expected to cause external irritation, as would herpes (which you did not ask about but may be thinking of) as well as internal discomfort.  On the other hand, problems like kidney stones or a drug reaction (the drugs themselves cause irritation in some patients) might cause problems.  Of these, the problem most likely to cause intermittent discomfort(you state that you sometimes have discomfort but not always) is kidney stones.

At present, my advice is to see your doctor.  Probably best if you  have not urinated for several hours before you do so that a urine specimen will provide the most accurate information about the presence of internal abnormalities.  Gonorrhea, is unlikely however.

I hope these comments are helpful.  EWH

Sorry if I was not clear.  If there is no visible sign of possible herpes, I would not be worried, nor would if feel the need to refrain from sex with my regular partner. 

While many health care providers worry that gonorrhea or chlamydia could cause prostatitis, the fact is there are no scientific data to prove that this is the case.  I would not worry that you have STI-related prostatitis.  Further, I would add that while all too often health care providers make vague references to prostatitis when they encounter genito-urinary complaints they can not explain, the fact remains that the best studies of this entity suggest that STIs cause prostatitis rarely if at all.  EWH