For about 5 mins when i would breath in i would get sharp pain in side of neck & chest n lower left side of back why would this happen ?

Ice or heat,rest: pain that occurs with breathing in can be Pleurisy, where lining of lungs are inflamed & breathing in is painful. Also pain could be due to muscle spasm, paraspinal muscles along the spine can spasm, along with muscles left side of neck, causing pain. Rest & take it easy, try OTC aleve (naproxen) 1 tablet with food twice daily for a few days, see MD if no better. Physical Therapy helpful if muscle spasm