Hi ANgel's mom,
3000 Ferritin is high but it is possible to get it down with diligence. for that you have to be very regimented and strict. The chelation should only be skipped when there is fever. There should be no excuses to skip the medicine for any other reason. You mentioned the dose as 400mg/day. is it exjade? what is her weight? with exjade, now there is no food restriction. so it should be possible to give her the medicine anytime of the day with food. In fact it is better to take the medicine with food.
In my opinion, right now, focus should be to get back on track on chelation with the right dose. there should be no missed days. if there are side effects, please tell us and we can suggest if that can be controlled. Once she is regular with chelation medicine, then you can introduce multivitamins with trace minerals and vit D. But that can probably wait till the chelation routine is in control.