Hello, sarcoidosis can cause neck pain due to involvement of lymph nodes while shoulder joint pain either due to inflammatory reaction or due to cyst formation in bony area. this disease progresses through three phases 1. inflammation 2. granuloma formation and 3. fibrosis of involved organ which may become fatal, but symptoms improve with time. He should be under regular check up with his health professional, eat fresh fruit and vegetable, drink plenty of water and 6-8 hour sleep, quit smoking, avoid exposure of dust, fumes, chemical, excess calcium and vitamin D supplements. Thank you for consulting HCM.