My anus together with the canal and private parts is very itchy, a specially at night . when i am relieving myself the pain from the anus is unbearable . what could the problem be ?

Need to examine: Two possibilities, hemorrhoids and pinworm. Do not rule out pinworm just because you are not a child. It would require an examination and a test to diagnose or rule out pinworm. You may talk to your pharmacist for an over the counter treatment for pinworm. If that does not help, do see a doctor. Wish you good health!

Pruritus Ani common : Itch, stinging, burning of the perianal and surrounding areas very common without any specific infection or skin rash associated. Anti-itch and steroid ointments can be very helpful as well as using a quality lubricant, ie. Aquaphor daily especially after a bowel movement.