horrible constipation

Can anyone please give me some advice on how eleviate this? My little one is sooo constipated. We've tried Apple, prune juice, karo syrup, castor oil, warm baths while rubbing her tummy, prunes mixed in with her foods. I keep offering her water and her breastmilk. We took her to the ER last night and they pretty much told us to continue with the infant glycerin suppositories, they are not helping. Her stools are so hard that we have had to help her get them out very gently with a thermometer. She's in so much pain! Can anyone else relate to this?