DS had bad chicken pox 18m ago, he had just turned 3 too.

He also has bad eczema so we ended up using a lot of oilatum in his baths (we had 2-3 hour-long baths together every day as they calmed him a lot and helped with the hydration) and also gave him baby piriton to stop the itching. Yes, it is an anti-allergy, but the doctors said that was great and had me make DS a drink of water laced with baby piriton, neurofen jr and calpol. Distraction is also great - we had Cars on full time (even all night) for 4-5 days.

Things to watch out for - temperature that won't cool even stripped/outside, laboured breathing (the spots get in the lungs too), lips turning blue, spots getting infected when they've scabbed over (not always due to scratching: DS had problems just rolling over in his sleep).

Your DD shouldn't get them as bad as DS, but if you have any worries get her checked out - chicken pox can kill, even at age 3. I would recommend co-sleeping too, just so you can keep a close eye overnight.