Novice with aching hands Ask your novice how much other manual work (yes - I mean with the hands) she does elsewhere. If she is accustomed to using hand operated tools and equipment (not electrically powered) e.g. in gardening, DIY, car maintenance, laundry or cooking, then her muscles will be used to gripping and releasing tools and equipment, firmly with the necessary strength. Now, with 'labour saving' devices fewer people build their manual strength and dexterity so they may well find ringing takes time to build the technique. Traditionally everyone used their muscles in every day tasks, but who now wrings by hand several double bed 100% cotton or linen sheets routinely on the weekly washday? As she has already consulted her Dr, hopefully she has avoided the risk that something more serious may be amiss.
As a tip, she says her right hand is dominant, then advise her to develop consciously the use of her left hand to equal effect. Also check her rope hold - she may well be using her right hand predominantly, Many ringers use their left hand for the tail end through the palm and not just under the thumb so rely on the right hand almost entirely for the sally. This means the left hand is not gripping the sally fully especially with small hands or fatter sallies, consequently tiring her right hand.