I am going to suggest you think about your body for a few minutes. It is usually something that is causing the issue.
Constipation. If the bowels are full or clogged the need for food goes away.
Sinus drainage, the goo fills the tummy up and makes the thought of food gaggy.
Feeling overwhelmed and frenzied can also make the thought of eating nauseating too. It makes the food just different, it may be that it's a control issue going on inside your mind too. That your mind is making your body just not want to eat, it could be an illness coming on, depression occurring, stress related, and sometimes my body just doesn't want as many calories. Each time I start a new job I find that I lose 20-30 lbs. the first few months. I think it is because I have so much on my mind that my stomach just takes the back seat.
Calling the doc may be something to wait about. If you are still not able to eat tomorrow afternoon then by all means call and ask them about making an appointment for Tuesday. In the mean time try to drink some 7-Up, I can't stand Sprite when my tummy is upset. If you can drink stuff try some Gatorade (the pink Rain is really good), it is basically flavored salt water but it does have some other stuff in there too. Sometimes it is the oddest thing that will taste so wonderful too. When my granddaughter was in the hospital this Summer with Strep she fell in love with plain iced tea. She drank it by the pint but still, it was all that she wanted for days.
Having a good check up with blood work and perhaps an X-ray would rule out some basic health issues if this continues. The blood work should be a total panel, like for thyroid, infection presence, blood levels of stuff like cholesterol, sugar, blood proteins, calcium, electrolytes, chloride (mine is always low), kidney function, and liver function. These blood tests will rule out anything serious if they come back normal. If not then the doc will have a starting point to go from.
Good luck getting hungry by morning!!!