Amielou,
I would just nurse them more frequently, but if that didn't work I would put them in a warm bath and massage, starting at the top of the outersides of their upper thighs and with gentle pressure rubbing downward. I know it doesn't sound nice, but I would let them go right in the tub, and then just scoop it out with a disposable cup to be poured into the toliet, wash out the tub, and then put them in again to get cleaned up afterward. Of course, if she doesn't like baths then maybe just laying her down and doing the massage will help.
I have heard that diluted prune juice is good, if they will take it, and the pear and apple too, but I have never tired these. I heard that a little castor oil helps too, but again I have never tried this and I'm not sure it would be good for a child her age. I have also heard of mothers flushing them out, but never have...and probably wouldn't since I don't know how. I would say, if the juice, the bath, or the massage do not work, and If things go on too long, let the doctor do something for you.
The Lord bless you.