Luke, I think you should do a check for vitamin B deficiency (B1/12)
Interesting, I've just had a read. By a check do you mean go for a blood test? I do eat a lot of Meat, Egg's and Dairy products which are sources of Vitamin B, I also take multi-vitamins.
I am tired a lot of the time which I thought was to do with lot's of training/exercise, work, being a dad and lack of sleep...
I also have quite a low level of body fat too which I don't think helps with the tiredness.