No STD causes such symptoms involving the scrotum and inner thigh, with the very rare exception of syphilis, which can cause a rash anywhere on the body. But if you don't have a similar rash elsewhere, especially the palms and soles, syphilis isn't a worry. Anal bumps could be warts, but the other symptoms don't sound like that.
I don't get into speculating about causes of symptoms other than STD. Any of the hundreds of conditions that can cause rash anywhere on the body sometimes can affect the scrotum. Possibilities include
tineaAthlete's foot
Athlete's foot, tinea pedis
Dermatitis, reaction to tinea
Folliculitis
Jock itch
Ringworm
Ringworm, tinea capitis - close-up
Ringworm, tinea corporis on an infant's leg
Ringworm, tinea corporis on the leg
Ringworm, tinea manuum on the finger
Ringworm, tinea on the hand and leg cruris (
jockJock itch itch), lichen planus, eczema, and various superficial infections.
You'll need to see a health care provider. Or you might see what Dr. Rockoff has to say on the dermatology forum. (If you do that, be prepared to add some more detail about the rash in both locations, such as the extent, whether the
testicularTesticular biopsy
Testicular cancer
Testicular torsion
Testicular torsion repair
Testicular torsion repair - series portion is reddened, whether there is any flaking, and so on.)
Regards-- HHH, MD