I've felt exactly the same in my job for about 2 years. I'm now job hunting as I leave in June (ish). It's the best thing I can remember doing! I feel much happier already, and I am enjoying doing my CV and writing letters. It took a long time to make the decision, but the feeling is great when you know there is no turning back.
If you need a change mate, only YOU can make it happen. If you are unhappy, get a new job. Get careers advice from professional people, find something new if you fancy a total change. Work out what qualifications and experience you have, and how they can be used to sell yourself to a potential employer.
There are other websites for jobs, such as Monster.com etc. Give them a try.
I suspect you may be able to earn more than your current salary, so research what different companies offer to people of similiar qualities as yourself.
Honestly mate, why live an unhappy existance? That feeling in the morning when the alarm goes off and you really can't face work. It's horrible. But you've got to go. And it lives up to expectations. And on it goes.
Hows about enjoying life again? If that appeals then seek out advice!!
Anyway, good luck mate!
Paul