I'm kinda going through the same thing
Something is stressing me out and I don't know what
Why not get those cheapish anti-stress pills from your drugstore or something, I used ones called calm when my gf told me to take them, they helped actually,
Basically work on getting rid of the stress and it'll ease the not being able to eat thing
Go to a doctor and tell him/her about the problem they'll probably prescribe you medication for your tummy or/and for your stress I'm just not sure about the mood swings..
Maybe a side-effect of not eating right anymore?