I felt like this for a few days, I too had a real headrush and nearly passed out once too. Then after ahving ran 6 km for 3 out of 7 days the previous week, could hardly get up the stirs to the gym last week. Thought I was going mad! Then the sore throat started, and felt really rouhg. Yesterday strp throat was diagnosed. This is some sort of throat infection. I ahve started antibiotics but still feel so so tired. I'm sure its just a bug or a virus. Rest is what you need, but so hard with kids. I am a single Mum to two, so know that they don't start doing stuff themselves cos mum feels ill, not that young.