Rash on back of hands

My four year old daughter has a reddish rash on the back of both her hands. This rash comes and goes and we can't seem to pinpoint the cause. We do know, however, that the rash is worse at night, that soap does not cause discomfort, regular scented lotions do cause burning, and hypoallergenic lotion does not burn but does not help either.  At first we thought it was wind burn, because it only comes out at night after she's been inside for several hours, but it will be gone before morning. Her skin feels thicker and is slightly bumpy but not pimpley.  
We just want some ideas so we can get it to go away.