What caused the peeling of the testicles?

Tinea cruris is

caused by dermatophyte infection such as Trichophyton rubrum, Trichophyton mentagrophytes, etc. Dermatophytes invade testicular mucosa, causing red spots, papules, and desquamation on the surface

.

Psoriasis

psoriasis may be related to immune abnormalities, genetic factors, etc. After the disease, the testicular skin may appear red patches, usually covered with silver-white scales.