There are many reasons you could be tired and achy, more information would be helpful to understand what could be happening. Weight, age, and other health issues could cause you to be tired and achy especially if you're not use to exercise. If you're achy because of physical activity, I recommend L Glutamine, it will help with recovery.
It sounds like you might not be eating enough calories to keep your body going.
Have you actually calculated the calories you need/day and are you counting them?
There are also some medical issues that can cause tiredness that's not relieved by sleep. Those include hypothyroidism and vitamin B12 deficiency.