I've been telling you for as long as I can remember that megadose vitamin supplements aren't good for you ;-)
Think seriously about Glenn's point, Damian. What are you eating? No amount of pills will compensate if you're not eating enough for the level of training you want to do, or if your diet is full of junk food. Some runners DO get away with eating next to nothing or eating nutrient-free pap, but most of us can't.
wWhat were you doing in the way of training before you ran out of steam? It's all too easy to overtrain and get "burned out", with physical and mental fatigue and lack of motivation for exercise as a result.
And it would be worth asking your GP to have a look at you and maybe do a blood test to make sure you're not anaemic or hypothyroid.
Hope you feel better soon.
Cheers, V-rap.