Thanks for posting,
From your description it will be hard to tell exactly what lesions you are having without seeing them. The white patches are most likely due to a fungi infection/dermatophyte also known as tinea cruris
and if increasing in size then it is definitely an infection.
My suggestion is that you should consult with a dermatologist
who will first examine the lesions, confirm the cause and provide you with appropriate treatment most likely antifungi cream (such as miconazole
cream) or steroid
cream (such as hydrocortisone/betamethasone
Other possible causes could be ruled out such as bacteria, viral or parasitic infections of the penis area.
Hope this will help