Not feeling hungry?!

I'm experiencing something pretty strange. For the last few days, I just haven't been hungry. Yesterday I got up and went for an 8 mile run and then had some eggs and grilled ham, and then at 11pm I realised I hadn't had any lunch/dinner and wasn't even hungry for any. I eventually ate some cucumber and humous but it felt like a chore.

Today has been similar - handful of strawberries for breakfast, small salad for lunch and then barely managed a bowl of soup for dinner - after an hour long circuits class. I can't work out why I'm not hungry and it's making me a bit nervous because I work out 6 days a week and I'm not really sure what my body is running on at the moment.

What do I do? Do I force myself to eat even though I don't feel like it/want to, or ease back on the exercise and hope my appetite returns to normal soon?!