my penis head gas gradually been turning white over the last few months, no pain.
only had one sexual partner and have been with her for years.
You should consult a urologist soon.
What you have is likely to be a severe skin condition. You can either go along to your Regular / Family Doctor / GP who will likely refer you to a Specialist, or if you live within easy travelling distance of one of the larger Walk-In Sexual Health Center’s go along and ask to see a Urologist or a Dermatologist.
The best specialist to see would be a Dermatologist specialising in Genital Skin Disorders - you can do an online search for one in your area - if you live in the UK these are the kinds of terms I would use …
a large city, area, or region of the UK in which you live - NHS - Genital Skin Disorders
… if you get a hit for a hospital department that you can travel to, phone them up and ask whether you can refer yourself or whether they need a referral from your GP / Regular Doctor …
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When you have seen a Doctor or a Specialist please update your Forum Thread here, I have an incurable skin condition of the penis myself and I can guide you further once you have a diagnosis of what you actually have …
Visit dermatologist as soon as possible since it is your best bet to find out what it is and receive proper treatment. Urologist might be other option but they tend to send people to dermatologists since they do not deal with skin conditions and this is skin condition caused by bacteria or fungus most likely.
Sometimes they hit right treatment immediately, sometimes swab test for bacteria and candida presence is required.
The foreskin of the penis is an area where many skin conditions can be involved. This does not sound like a standard sexually transmitted disease, however looking at the lesion would be required to make the diagnosis. While it would be unusual for gonorrhea or chlamydia, other sexually transmitted disease such as granuloma inguinale. Herpes normally looks more like vesicles. Syphilis is normally painful. Regardless, I would take appropriate precautions until you can have this evaluated.