nzfiona,
if you still have no appetite it may be a good idea to listen to that. Even if are losing weight. If have no appetite it might be because your body needs recovery time still.
I agree about avoiding fats. And the gluten and dairy foods. And egg is often allergenic too.
One approach is to only eat raw food, because when raw the natural enzymes in the food can actually help digestion. Eat little amounts of fresh raw foods. Pears, sweet juicy carrot, a few sunflower seeds, pecan nuts, lettuce ( there's some sort of soothing thing in it), cabbage juice, ( I kid you not; it's supposed to be super good for gut healing, and actually tastes surprisingly nice, especially when ill !) , carrot juice, lightly stewed/microwaved apple ( the pectin in apple is good/reparatory for irritated digestion), celery, almonds.
And chew heaps. Chew as if each mouthful was a meal.
A gut infection, especially followed/treated by antibiotics can literally trigger, or uncover, food intolerances. The best thing is to take it very very slowly, and listen to your body.If you aren't hungry don't eat, just make sure avoid dehydration, with very very weak mixtures of fruit juice and water, and very lightly salted vegetable juices.
Sometimes after severe gut infection and antibiotics need to replace gut bacteria to restore full digestive capacity. Takes time. Health food shops may have some supplements for that.
Lots of luck. o