I have a bark brown spot under penis. 1mm by 5mm. I'm circumcised and have good higene. Thoughts? Post e mail if you want to see and help. Thanks.

Freckle? On the shaft or the head? If it is on the shaft, it may simply be a scar or freckle. If it is changing in size, it should be evaluated sooner than later. Otherwise, you can ask your doctor during your next exam.
May Not Be Serious. It may simply be a dry patch. The head of the penis is mucosal skin (like inside the mouth) and once you are circumcised, the skin attempts to "toughen up." it may also be the start of a flat genital wart. It would be best to have it checked out, but it is not an emergency.
? Melanocytic nevus. Might need to be removed, send fotos to my email and I will comment.