Dear sir,
after reading the history the most possible lesion is either
herpes infection or
folliculitis.
the following points should be taken into consideration :
1- on the penile shaft there is a region where there are some hair follicules, these follicules can get infected by local bacteria and cause folliculitis, the head of this raised lesion will be yellow and cause a little pain. It is easily diagnosed when seen. the treatment is local fuscidine (dont use fuscicort because it contains cortison and we dont want that due to the other diagnosis which is herpes that will flare up on
cortisone) use fuscidine 3 times daily on the lesion till it goes away.
2- the other possible diagnosis is herpes infection which is a sexually transmitted infection, the test for HSV2 is not part of the usual
STD pannel, that is why i highly doubt the test for it was done. the presentation will be painful multiple small lesions that might crust. since now you had one lesion if this develops to become multiple small lesions around it with
tingling sensation on the skin and pain then a course of
acyclovir can be prescribed even though it wont be as beneficial at this point. It can be diagnosed by culture, PCR, tzank smear.
Best regards