Hello, Your symptoms may be indicative of developing osteoarthritis or compression of the trigeminal nerve. Facial nerve may dilate due to eating ice-cream that is cold and cause nerve compression and hence pain at collar bone. Avoid eating food or taking drinks that are too cold. Sometimes, acid reflux or formation of too much gas can also cause pain under the sternum radiating to the collar bone. For relief, take antacids or PPIs, avoid constipation, Take adequate amount of water and fluids. Take fiber rich food. Avoid taking oily, spicy food, packaged food, processed food, etc. Since the pain is specifically on the left side, you are advised to get clinically examined by a GP, get cardiac function tests, lipid profile, EKG, echocardiography, stress tests, etc., done to detect any developing CAD, coronary artery disease. You should get the cyst examined. Since it is becoming painful and hard, a biopsy will have to be done along with other tests. The treating doctor will either give conservative treatment or recommend removal by surgery, whatever is the best for you. Do not neglect yourself, get treated. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Nupur K., General & Family Physician