Experiencing pain in my triceps. how to get rid of this pain ?

Recently I have been experiencing pain in my tricep. When I go about my normal duties I do not feel any pain but when I lift my arm above head high or make a sudden movement I have a nasty pain in my Tricep & sometimes I can feel it in my shoulder . I think it is wear & tear because during my work I lift heavy bins & this particular arm does most of the work lifting & tipping these bins. My query is what could I do to improve this situation & a few weeks ago at work I bent my thumb back & I thought I had broken it I don t think the two are linked.