it seems you are not on medications?In that case black spots may be skin problem for which consult skin specialist(dermatologist
), he may prescribe skin ointments
etc for relief depending on cause and diagnosis.
As for back pain
,get Xray of back region and consult orthopedist, it appears it is stiffness
during rest period and mobility in day activity lessens it - so back strenghthening exercises may help-but get evaluated with x-ray if there is any underlying disease of spine or associated structures in the region.
I can advise more after these prelims plus divulge your past treatment record if any