When i try to fully extend my arm i can feel a little discomfort at the shoulder should i get an mri or consult w a specialist ?

See Dr. FIrst: Have a doctor evaluate you and they can order the test they feel is most appropriate for your condition. Good luck.

See your clinician: See your clinician first, who will do a thorough history of the problem, and a physical examination. After that, they can formulate a diagnostic and treatment plan, which would include targeted tests and procedures as well as appropriate specialists if needed. Hope that helps.