You guys seem to have everything under control here but just thought I wold add my little story.

When Evan was about 2 and a bit he had a bad tummy bug. During this he became constipated. He was throwing up all the time, I think none of the fluids he was having was doing more then just wetting his mouth (twice). After the tumy bug settled he still continued to vomit at least once during the night about an hour after goign to bed. I kept taking him back to the dr saying that he hadn't poo'd and could that be the reason for his vomiting. She didn't think so and send him for an ultrasound and xrays. This revealed a heap of poo in there. In the end the poor little bugger was in so much pain when the poo finally made its way out that I ended up sitting in a hot bath with him lying on me while I rubbed his lower back. He passed his poo in the bath, which was real fun! I felt so "Clean" not! But it got it out. But he was very tentative about going for a poo for awhile there but he soon got over it.

I personally think that the cramping that you get in the tummy when you are constipated is the same type of pain you get while in labour! Well it is for me anyway, not as bad as labour but for a 2 year old I'm sure it is!