It sounds like a Pinworm-- they hang out in the colon area -which is why your enema shot it out. Good thing to. That means one less worm to lay eggs there. They are off-white like that , too- and the reason your anus itches at night is because of them. Rubbing some crushed garlic on your anus -- while keeping your underpants on or a bandage over that area, will keep them from itching that area. The garlic will burn a little at first, but you will have relief of itching and be able to sleep.
My sister and I had these when I was younger. I wish I knew about HumaWorm and herbs back then -- instead I used over the counter pinworm medicine that temporarily killed them but never really got rid of the entire infection-- plus also destroyed alot of the good bacteria in my gut too in the process.
HumaWorm will help ya!-- Hang in there!