Hello dear
Understand your concern.
Severe anal itching could be associated with 
Excessive moisture, sweat, pressor on sitting, rubbing and scratching and 
frequent 
loose stool, diabetes and yeast infection and 
Worm infection of intestine
You take following advice
1. Maintain hygiene after defecation, first wipe with simple plain tissue paper and wash properly with gentle warm water
2. Do not keep wet, dry the anal part with pure cotton towel
3. Change the inner wear after exercise and work out
4. Wear pure cotton loose underwear
5. Eat healthy diet with lots of fiber
6. Avoid constant sitting to minimize pressor.
7. Take warm water sitz bath
7. If not resolves
Then consult the physicain and go for 
stool test, blood sugar, CBC, ESR, anal swab test 
You can apply prescribed steroid ointment: 1 % 
hydrocortisone plus 
clotrimazole ointment
Hope this may help you 
Contact HCM for further health query
Best regards
Dr. Sagar