There is a juice called Plumsmart that is like prune juice but tastes better and works better. It is expensive, at least it is here, but it does help.

I think WC is right and you're going to need to do a suppository or enema to get things started. Those never work for me so when it is that bad I drink 1/2 bottle of magnesium citrate (cherry tastes a lot better than lemon) and that works. You'd need to do that on the weekend though or be able to work from home or something; it can take a while to stop working.