I've had this squeezing pain in my heart for 24 hours now. i've taken tums (calcium carbonate) and gasx, no help. it hurts to breathe, lay on left side too. help?

Be evaluated: With these symptoms you should see a doctor today to exclude any life threatening causes.

See doc: The fact that your discomfort is positional and changes with respiration makes it unlikely to be a life threatening cardiac issue. A blood clot to the lungs (pulmonary embolus) and pericarditis need to be ruled out however.

.: It could most probably be gastritis or costrocondritis (inflammation or ribs). But with you having pain on breathing and on lying onto your side, you better check with a physician to see if the pain is from heart. And you may also need an examination to confirm origin of pain.