Hi Tigger
I'm no doctor - there may be any number of reasons why you're feeling this way
If you're worried or concerned maybe a trip to the Dr might be a good way of at least setting your mind at ease.
I usually give this link out when PAWs is mentioned tho - all I suggest is you take a read and see if any of it sounds familiar or applicable to you
PAWS « Digital Dharma
Hope you feel better soon
D