Ohh I can sympathise as I had the same problem for about 2 weeks after giving birth and it was awful. I couldn't believe that not pooing could be so painful!
I tried all the different products that were recommended to me and nothing seemed to help much... metamucil, agiolax granules, agarol liquid, coloxyl with senna... In the end I really found that the only thing that really seemed to help was good old prunes! (Lots! )