I've had pain in my left shoulder/upper back for 3 weeks. also, pain in my left upper arm, with some tingling/numbness. massage helped some. ideas?

Brachial plexus: Need a full exam including an EMG to check your brachial plexus.

Could be your neck: Have your doctor check you for neck problems which can press on the nerves going to the shoulder and arm. It could also be coming from a muscle spasm in he upper shoulder.

Massage and therapy: Try massage and physical therapy for muscle relaxation. Sometimes an anti-inflammatory or muscle relaxant can also be of some benefit. If no relief, you may want to consider an MRI of the c spine and left shoulder. Tingling may be due to some nerve impingement from the muscle spasms.