If it's any mineral deficiency, you might want to do a blood checkup.

maybe protein/breakfast shakes? if you don't want to eat then you can still get the nutrients from something small (i know someone already said this but it's true)

I'm feeling the exact same way, and I do think it's because i skipped several meals this week. So i think like others that a second meal on lunch would be good to improve your condition.

Consider any medications you may be taking too. Worth asking a doctor about side effects.

Maybe meal replacement shakes or something like that would help? Just to get the nutrients your body wants.

You might have some kind of vitamin or mineral deficiency

Perhaps it's down to a lack of a specific vitamin/mineral?

Ask your doctor about it. They'll be able to get to the bottom of it, I'm sure.

I have to set alarms to remind myself to eat but I usually just have small stuff during the day and then a decent dinner.
Granola bars have been my saviour for when I don't want to eat but should eat something.

Oddly enough it’s better to have light snacks throughout the day than larger meals

cooking sometimes made meals more enjoyable to me
the fact that i was the doing it gave it some purpose and it also allowed me to eat things exactly how i wanted
even if i had no apetite i tried eating each 5 hours or so.
eating can be complicated..

Maybe try introducing a second meal to your body little by little? Like just a half of a slice of bread, or a few bites of cereal.