dermatitis pigment wont go away?

[anaboliQ]

I have battled what appears to be dermatitis for a few years now. The condition began with small red itchy areas in my armpits and a small area in the center of my chest over the sternum. The flare ups would come and go and weren't really difficult to live with.  The armpit rashes have disappeared completely and are no longer visible.  The lesion on my sternal area waxes and wanes and sometimes becomes active after exercise. The lesion is never scaly, but when active becomes moderately itchy and tender.  Over the winter, a small lesion under my nose and above my lip appeared.  It would become dry and flake, but after moisturizing and UV exposure keeping the area free of moustache it too has disappeared.  

About 2 summers ago, I had shaved my head and had small itchy lesions all over the place consistent with seborrhoeic dermatitis.  The rash spread across the back of my head between my ears underneath the area where the skull meets the spine to the lower part of my hairline on the neck.  I began using intensive treatment shampoo and have been free from itchy lesions since, yet the area is still a large red patch.  The area doesn't seem to be active with symptoms (not raised, itchy,scaly or dry) yet the pigmentation remains constantly.  It is not storkbite or an inherited pigment problem as it appeared when the dermatitis symptoms arose.  

I have a dermatologist appointment in July to find out my options for clearing it up, but I am wondering if this is common problem for others with seborrhoeic dermatitis.  If so are these discolorations permanent? If not, what treatments will eliminate it?

[anaboliQ]

^^^ actually I meant tinea versicolor.

[anaboliQ]

any chance this patch on my neck is actually pityriasis rosea?