Hi, a nurse friend told me a patient in the hospital couldn't either for days and she gave him a good amount of hot prune juice and later he let out a whole bedpanful with a lot of commotion. If that doesn't work better get checked real soon.
See my post on Apple Cider Vinegar. Its a pain at first to get the Apple Cider vinegar...but i promise you, if you continue to have this problem..it will be the best thing you ever bought for 11 dollars.