I m a celiac but can t poop?

Your body is adjusting to the new diet. Give it time. In the meantime take some digestive enzyme supplements and drink dandelion root tea with plenty of water. Please be patient. Going gluten free will be the best thing that you have every done for you health once you get used to it.

General advice for dealing with constipation is at the first link. You might have cut way back on fiber by eliminating grains.

If you have really hard poop that hurts too much to get out, read the treatmetn description at the second link.