What could cause my body to ache all the time and especially in the evening when i rest?

Many things: There are many conditions that can cause body aches - it would be important to now if there are other symptoms certain infections, autoimmune disease ( body attacks itself) or specific muscle conditions. A common DX that can cause you to hurt in many different area or (all over) is called fibromyalgia- it is usually assoc w fatigue and sleep disturbance. But i recommend you go see your dr.