Welcome to HCM
We understand your concerns
I went through your description. I suggest you not to worry too much. The stinging or burning pain in your penis on standing could just be due to some mild inflammation in the urethra
. Climate and lack of water could cause this. Therefore, drink plenty of water and see for a day. If still problem persists, see a physician.
The discoloration may have nothing to do with the burning until there is direct burning or itching at the area of discoloration.
Hope this clears your doubts. Available for further clarifications.