Hello, Thanks for posting us your query.
Fore skin being tight can lead to a condition called phymosis, in which there is no retraction of the prepuce over the shaft of the penis. This leads to further tightening of the foreskin, thus decreasing the possibility of cleaning the space beneath the prepuce. The urine droplets, normal physiological secretions, including the semen get collected in that space giving rise to what is called Smegma. Since it becomes difficult to clean the area regularly, the collected secretions get stale and infected over a period of time.
It turns into a mixture of bacterial and fungal infections, accentuating the condition. In your case you might be suffering from a mild degree of phimosis. On and off appearance of your symptoms guide me towards to the above mentioned condition.
Furthermore I would like to explain the causes of White penis as you described.
1)collection of Smegma, which appears in similar fashion once dried up
2)Fungal infection of the penis- most commonly Candidal.
3)Leukoplakia which is a pre-cancerous condition
It is seen as a consequence of unhealthy maintenance of the prepuse and infection with Human Papilloma virus.
4) Other infections that simulate this condition are syphilitic ulcer, Balanitis ( infection of the glans penis ), Posthitis (infection of the inner surface of the prepuce).
If the problem is with the phimosis, there will also be a thin stream of urine, then the proper step would be to widen the opening by a simple surgery.
If it is balanoposthitis, oral antibiotics will be of help. It is advised to consult your Physician and confirm the diagnosis so that it can be managed carefully without any unwanted consequences.
Hope this helps.