Left side back muscle strain feeling btr w/ muscle rub, large knot. Better now, but have a numb/tingle feeling under left breast on rib cage to back?

Muscle verses nerve. Continue to use the rub, heating pad to treat the strain. If the numbness and tingling doesn't improve, the possibility of thoracic radiculopathy should be considered. Thoracic imaging such as MRI can be utilized for further work up.
Sore muscles. Hi, Thank you for your question. It sounds like you have muscle aches. Try some anti-inflammatory like ibuprofen or Tylenol. If you aren't feeling better then be evaluated. Hope that helps..contact me if you have any other questions :-) Dr. M.