Hello,
Rash on the thigh after sex is commonly due to Jock Itch(
Tinea cruris). Jock itch can be transmitted from one person's groin area to the groin of their partner, it affects the other parts too as ringworm.
You can apply ointment
Clotrimazole in the areas affected. You can also take a course of oral anti fungals.
Avoid sex for a couple of days, take care of your hygiene. Keep your private parts clean & dry.
For safe side you can get STD test done to rule out any STI. Pain, tingling & discomfort in the groin may occur due to
epididymitis,
testicular torsion, hernia, UTI or Kidney stone/ kidney disease.
You are suggested to get clinically examined by a
Urologist. Get blood, Urinalysis & required imaging(MRI/CT) tests done to rule out the factor causing discomfort. Your treatment will depend on the pathology detected.
Hope I have answered your query. Let me know if I can assist you further.
Take care
Regards,
Dr. Nupur K