Round red/pink rashes around buttock area and tingling sensation down pelvic and thigh area. no other syntomptoms.

Rash and tingling: Sounds like a possible case of shingles. See your Doctor ASAP - Earlier detection and treatment will reduce the chances of long term pain issues in that area.

Dx uncertain: This can't be diagnosed with the information that is available. A history, physical examination & other studies may be needed to determine cause/causes. Once accurately assessed a treatment plan can be developed.