When things got really bad I used a glycerine suppository to get the first blockage out, then took lactose after that when I felt it starting again. I remember being in such pain, that I needed a quick solution. I found it very bad when working in an air conditioned office, as it is easy to not drink as much as I should have as the temperature is cooler.
I have some glycerine suppositories in the cupboard in case I get desperate, someone said the Lactolose wasn't ok when pregnant? If it is I'll give it a go.