Often a person can pick up a fungus on their feet - athletes foot—from going barefoot in a public place. When a person puts their underwear on it pulls the fungus up to the groin— jock itch.

Throw out old tennis shoes

Wear flip flops in public places

Put socks on before underwear

Can be related to weight or tight clothing. Would need to see it.

Age does not gives special privilege against skin diseases. The reverse is true.

Sweating, tight clothing so groin can't breathe, body heat and secondary yeast infecion

Jock itch doesn't have to do with age, it's basically a yeast/fungal infection. It's the same stuff that causes tinea versicolor, tinea pedis (foot fungal infections) (tinea corporis)- it's basically areas you sweat in. To avoid it- if you sweat, shower shower shower. Selenium sulfide works great, OTC in selsin blue. Of your doc's giving you a steroid with an antifungal, they are actually doing wrong.