It sounds as though you are worried and have been scrutinizing your penis more closely of late than in the past. In the process, you have notice variation in the color (redness) and small bumps around the glans. The bumps sound like normal structures which often go un-noticed for long periods of time. Some such structures are called pearly penile papules, others are simply glands. They are not disease.
You are right that following receipt of oral sex the most likely STDs are gonorrhea and NGU but your descriptions do not sound like these problems.
There are no STDs that cause the penis to form red dots or red areas that would last months. The redness you note may well be irritation.
The tests for gonorrhea and chlamydia are very good. If you have negative tests, you do not have gonorrhea r chlamydia. The tests are almost never false negative.
It does not sound like you have an STD of any sort. My advice would be to see your doctor and ask for his/her opinion. I would add however the Neosporin in particular can cause irritation and redness as a side effect of its use. Hydrocortisone can also cause reactions but it is uncommon; the one thing it can make worse is yeast infections.
My advice, ask your doctor. This is most unlikely to be an STD. EWH
any thoughts on what could be causing the tip of my penis to be sore, and any thoughts on a remedy?
thanks