Whitish discolouration on glans can be due to vitiligo, lichen sclerosus and even fungal infection. You may also be having fungal infection on the groin and thighs. Please don't use keto b as it contains steroid and should not be used for fungal infection. Please send photos using online consult option for proper examination diagnosis and treatment advice.

Your symptoms are suggestive of fungal infection. It will take time for the lesions to go and it will go progressively by lightening a few shades and eventually fading off. Follow up with your dermatologist in the time told to you or when the medications are over and there's no change, you should visit the dermatologist so that you can be examined and undergo the necessary investigations to find the underlying cause of the problem and have it treated accordingly. If the problem persists or worsens visit the dermatologist at the earliest.