Is it likely a child has leukemia if they have a lot of the symptoms, fatigue, body aches, pale, abdo pains etc but have no fever?

Symptoms: These symptoms are non specific In order to make a diagnosis of leukemia he will need a blood test and eventually a bone marrow to substaniate the diagnosis

No: Common things are common, like ineffective sleep habits or other minor medical issues.Uncommon things like leukemia do happen, but a proper evaluation can confirm or exclude it.