What kind of testing have you had done? I would assume you've tested for gonorrhea, chlamydia, NGU? What about herpes? Have they done a prostate exam? Have they sent your urine out for a culture? Have they actually looked at the area you are talking about?
Did they do any oral STD testing, like oral gonorrhea testing? You exchanged oral sex - did you also kiss?
Have you taken any meds? What meds have you taken?
When you have the tingling on your lip, do you have it on your penis at the same time?
Honestly, without knowing what testing you've had, exactly, it's hard to say what it is. It could be nerve-related, it could be just irritation at this point.
What has your doctor said about these two spots? When you've had the recurring burning/tingling/etc., have you had them in these spots?