Why do i feel a sharp pain in my chest when i breathe or bend down?

Pleurisy : Taking a sharp pain when breathing is called pleurisy. There can be many causes the most concerning is pulmonary embolus a blood clot your lungs more common ones are a viral infection which can include the flu or a common cold or a bacterial lung infection such as pneumonia. This should be evaluated probably whenever someone has pleurisy to make sure there are no serious causes