I would recommend taking senakot at night. It's very gentle and you shouldn't get stomach craps. Personally I wouLd avoid ducolax as these are laxatives and work differently! You could also try get movicol from your local pharmacy but I can't cope with drinking it but it is a still softener so very gentle.
Try slimmers tea or it's also called three ballerina tea. It's all natural senna tea and gives you no tummy pains and you have a normal poo ( sorry no other way to say it ).