Why Does Being Sick Cause Body Aches? - An Explanation

Question
I was wondering would you please explain to me: why do you feel achy when
your sick?

Thanks
C Barwick

Answer
in general, there is a whole body reaction to a viral or bacterial invasion, involving the white blood cells... they release chemicals that cause things to swell and get inflamed and typically, the achiness is the body's reaction to the illness.  Those chemicals help fight infection but also make you feel bad.