DD also 3 started wetting and also needing to pee every few minutes. This is apparently v common in 3 - 6 year olds and tends to be behavioural - for us it coincided with a period of being really stressed out with work. We tried to be very calm and matter of fact about it. Her dad got her peeing on the hour (learning to tell the time as well to space them out) and I used a sticker chart for the wetting - a sticker for every half day she didn't wet - and it only took a few days to sort out, although the info I've read on websites about the frequent peeing that it can take weeks....