My Wife Has Not Had A Bowel Movement In More

my wife has not had a bowel movement in more than three (now nearly four) days. Tonight she took two ducolax pills (5mg each) at about 124 Pm and by 2Pm had a very small bowel movement, but is experiencing cramping. Can I give her the prescribed dossag e of magnesium citrate oral solution to address the constispation and see if it relieves the cramping as well. In other cases where she had no bowel movement in at least four days thge magnesium citrate oral solution seemed to address the constipation problem?