I've had right throbbing shoulder pain for a few months now that comes on randomly throughout the day. what could this be from?

Time to get checked: Since the symptoms have lasted a few months a more detailed musculoskeletal evaluation is warranted. It may something a simple as tendinitis or impingement syndrome. Check with your pcp. A referral to physical therapy could be the fix you need.

Shoulder throbbing: Common problems include bursitis and rotator cuff tendinosis. They can cause throbbing. Less often it could be pain referred from the neck or from under the diaphragm.