I have dark patches or marks on my buttocks, inner thigh, groin area & legs. i had tinea cruris last year; marks not fully gone. need medication/help.

Hyperpigmentation: Most likely, your skin reacted to the tinea infection by darkening. When skin is damaged, it scars and darkening is one form of scarring. There are a number of different prescription creams that can be used to lighten an area, but shouldt be tested to make sure it won't make it worse. Other methods include laser treatments, chemical peels, etc, but again, these can also make things worse.

Skin Disorder: This can be as simple as tinea but even if it is, it has come back and over the counter products are not likely going to clear it up. Best bet is to see a dermatologist or your primary care doctor. They should be able to clear this up quickly for you and if it is something more serious you will be very glad that you got to the bottom of it.