Hello,
From the symptoms two important possibilities are pin worms and scabies. Other possibilities are moisture(due to sweating or frequent washing), the abrasion caused by clothing, the pressure of sitting, chemical irritants like laundry soaps, colognes and scented toilet paper, anal abrasions and fissures and skin problems such as psoriasis, seborrhea and eczema. Sometimes hemorrhoids will start off as red rash and anal itching.
Scabies is an infestation of the skin with the Sarcoptes scabiei mite. It is characterized by intense itching, usually at night and by small insect-type bites lesions on the skin. Diagnosis of scabies is made by scraping the skin and viewing the material under a microscope to see the characteristic mite or eggs.
If the symptoms are severe then please get it evaluated from a dermatologist. I hope it helps. Take care and regards.
If the spots are in the groin area, they may be tiny warts. I used Stridex Max acne pads at morning and night, and found that seemed to heal them, and they disappeared. Don't use Stridex in tender tissue of genitals.