My Dog Can't Poop. What Can I Do Or Give Her So She Can? I Think She Is In Pain.

This dog needs to be examined by a veterinarian.  There are many reasons why dogs have abdominal pain.  Constipation is possible but much more common in cats.  Foreign body obstructions are common in dogs.  This happens when dogs eat things like socks, toys, or rocks and they become stuck in the intestines.  Pancreatitis--often caused by eating a high fat meal or getting in to the garbage--is another fairly common cause of abdominal pain.
When dogs stop drinking they become dehydrated which makes them feel worse.  
Your veterinarian will do a thorough exam, assess pain, take x-rays, and do blood work if appropriate.  

My dog had the same problem about a year ago! You need to take him to the vet IMMEDIATELY... I don't want to scare you but it's so urgent that your little buddy could die... At least, that was my experience... It's better to be safe then sorry!

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Give you og lots of water so it can soften her/his system and it would e easier.

You need to go to the vet and ask them what they think is wrong.  The will pro bally perscibe you a laxative

Take to the vet asap  some mineral oil  could help mean time and then take to a vet.

Try to feed her some cod liver oil. Not to much or she my poo herself to death- just a teaspoon or two depending on her size.