Could be an allergy, I suppose. Have you tried simplifying her diet?
Her diet is fairly straightforward - 40g of wet food in the morning, small scoop of dry food for elevenses, 40g wet food in the evening, with the odd treat through the day. She seems to enjoy Whiskas and will always clear her bowl relatively quickly. Would like to maybe get her on some better food at some point, but as she's now finally settled into our house after a traumatic start am reluctant to do too much which may stress her out again