Hi there.
I checked out your profile and you have listed that you struggle with depression and think that you may be bipolar.
What you've described sounds like a start to a manic episode, but if your moods change so quickly, it could be a rapid cycling form of bipolar.
I've been diagnosed bipolar for several years now. And when I'm not on my meds, this happens to me when I am going into a manic episode. I don't want to eat and when I try to, I feel sick. I can go for days and days without eating anything and I won't even feel hungry. Sometimes, I forget to eat completely and have to leave reminders for myself.
I would suggest talking to a doctor about this and they will probably recommend a visit with a psychologist or psychiatrist to discuss the possibilities.
Of course, it's really important to rule out anything that could be physically wrong too.
If you would like to message me, I can tell you more about bipolar, if you would like.