I'm usually a good eater but I've all of a sudden gone off food?!?

I'm 18 and female and I usually enjoy meals. Lately though, I've been finding myself not wanting to eat... I've never really been hungry on a morning anyway but I feel sick and my stomach rumbles on a morning and I know I'm probably hungry but just the thought of food makes me feel queasy.

For dinner I can never finish my bowl of soup anymore, I feel so full.

& evening meals I can never finish either, whereas I used to always eat it all. I don't look forward to meals anymore! I couldn't even stomach one of my favourite meals last week- I found it awful!

I am not underweight at all, and I'm not very overweight either. I'm quite confused how I can't eat that much without feeling sick or put off.

Thanks.