[cypher]

Dry skin is quite common in older hamsters, it would be very unlikely that she would develop an allergy to paper based substrate & changing the substrate would be stressful which could just cause more problems.
Don't give cod liver oil, it's far too high in fat soluble vitamins & harmful for hamsters.
You can give evening primrose oil just a drop a day & extra flax seeds to help with dry skin, a little wheatgerm can help & you can also try a pinch of brewers yeast powder on food.
You can give baby food & porridge which she should be able to eat ok, there's a thread here about that.
Feeding Hamsters with Missing Teeth or Who Are Elderly
I wouldn't put sudocream or anything like that on her skin, if it's very dry a tiny amount of coconut oil is safe to use.