For my job i do a lot of writing and for abit now on and off i've been getting wrist pain on top on my wrist. what coul it be an how can i stop it?

May be overuse: If it happened after writing consider overuse of the wrist tendons in the back of wrist. If the non dominant hand is also painful or other joints hurt then it may be a more systemic condition and additional blood work would be recommended. Arthritis of the hand/wrist joints is possible. Initially, try resting it, using wrist brace, and see www.Osha.Gov/sltc/etools/computerworkstations/.