Hi, I have a dd who will eat really well one day and then not so for a few days afterwards. On Sunday, I was really trying hard to get her to eat pork sandwiches, but to no avail. Eventually, I whizzed up pork, greek yoghurt and some roasted vegetables I had cooked previously - she loved it (sounds ugh I know but she really did)! Annabel Karmel does something similar with cooked chicken and pineapple chunks, and that was yummy too! Worth a try?
Recommend what previous posters have said about peanut butter and eggs, I always try these with dd just to boost her protein levels.
Good luck, and try not to worry too much - easy to say I know, and this coming from the world's biggest worrier!