Ongoing mid upper back pain, spasms. Just did 14 day h pylori treatment. Pain in irritated back muscle and chest swallowing saliva. What could this be?

Needs Evaluation. To find out the source of this issue. Could even be atypical chest pain from your heart as opposed to GI pain from an ulcerated esophagus. Expect a chest x-ray, ekg to check out your heart, possibly an upper GI endoscopy. Don't try to diagnose this yourself. See a doc asap.
Muscle Spasm. Consider trying an ice pack, or taking something cold from freezer, wrapping in towel and place on muscle spasm area for 10 minutes.