I'm a 37 year old woman, I have anxiety disorder. Otherwise I'm in good health. For last four days I have experienced a soreness sometimes sharp pain in left breast. What could it be?

Chest pain. Chest pain could be due to muscular skeletal problems or anxiety. More serious causes of chest pain include ischemic pain, aortic dissection, pulmonary embolism, your internal medicine or pcp could offer the initial evaluation in non emergency cases and er physician in emergencies.
If in the actual. Breast tissue than it is not likely associated w your anxiety. Pain in one breast could be related to a cyst or a fibroadenoma. Injury may cause pain.. Exercise with a bra that is lacking in support is also a possible cause. Mastalgia is the term for breast pain. If it continues - have it evaluated by your physician. Take care.