Has your Mum started using any new products? ie miosturiser, soap, washing powder etc or has she been eating or drinking something different? or been around animals? all these things can also cause rashes & are worth looking into as a process of elimination
If it is eczema dairy products can also play a large part in flaring it up.....so it may be worth while on cutting down on dairy for a while
Hope she gets it sorted out soon