I strained a muscle that started in my shoulder. now i feel it in my neck. it's been 5 days. is this more than a muscle strain & i should be worried?

Probably not: If you strained muscle either by strenuous exercise or unusual activity or repetitive movements Apply Ice and take NSAID like Ibuprofen 3/day. Some of the Shoulder muscles ( e.g.Trapezius) are connected to the Cervical spine, one can experience pain in Shoulder, Neck and Upper back area. If this does not improve in 1 week or start getting numbness and weakness of the arm consult your doctor.

Strains: Muscle strains are often related and since the muscles are close in proximity and attach to each other, it is common to get traveling pains in closely associated muscle groups. Relax, heating pads, nsaids may help. Doc appt if severe or worsening.