What could cause extreme joint pain, weakness especially in leg and wrist with fatigue?feeling of having the flu but not actually having the flu??

Be seen: There are many potential causes, I would encourage you to be seen. Systemic inflammatory conditions can cause patients to ache in their joints and generally not feel well. These can precede a viral infection or can be associated with non infectious conditions like lupus or rheumatoid arthritis.. Consider being seen, and exam and labs can often find the cause.