What Causes Severe Pain In Arm While Stretching The Hand?

I was atched by pit bull dogs. My arm had puntchers and stitches where they bit and shock me. Went to hospital stitches and antibiotics were given 6months later my arm kills me when I reach for anything out of reach. I feel heat where scar is and down the mussel it is painful to the touch. I don t know why it is hurting again just cause I over reached. Will it stop or is something more wrong then I know. Why is the heat now its all healed up on outside and holes are too. Please I want to know how to get this to stop. Thanks