My penis is dry and flaky only when erect

For the past few years I have been dealing with this dry flaky skin on the head of my penis.

Underneath the dry flaky skin is a red rash. This red rash is most apparent when my penis is erect or when I get out of the shower (or when any blood flows to the head of the penis).

I have been in and out of the dermatologists office on a regular basis with no prevail. 

I was told to put on Cortisone cream, which relieved the dry flaky skin but never the rash underneath. The head of the penis is the only affected area and it seems to be the portion of the head underneath the foreskin (Since I am uncircumcised). The top part of the head which isn't covered by the foreskin doesn't have the redness or flaky skin.

I am looking for some answers and help please! This has really been affecting me mentally and stopping me from getting into sexual relationships. I have attached two photos. If anyone has experienced the same let me know, if anyone has any remedies that have worked for them please let me know to. If you can also diagnose this that would be of much help. Thanks

I've had the exact same problem. Over the winter, my penis was very dry, more so than ever before. I've had yeast infections and balanitis before, but this was different. Like you, when I had an erection the skin on my glans was flaky, and I had a red itchy rash that extended partially onto my shaft. I got moisturizers specifically formulated for penile skin, didn't help. Changed body wash, and voila! The issue was the soap I was washing my penis with was drying out the skin. I've found that the body wash you get at the store is not intended for delicate skin, and the chemicals tend to dry it out. So I recommend trying a natural soap and see if that helps. It worked for me, and my penis is very happy I tried it.