I want to say I love your kitty avatar! Mine does that even though he knows it's bad, haha.
One suggestion I might have, is it may be a mental thing. I find sometimes that I get 'cold' like symptoms before going to the gym, prompting me to think I should just stay home. I've learned to recognize that it's just me looking for a way out. Unforunately I let it get to me and went home due to a headache yesterday instead of going to the gym

It's like a mental game I play with myself.
Try drinking more water, take vitamins and still go. If symptoms persist it may be something underlying and you should see a doctor.