When i lay down and raise my arm up then down i feel grinding sounds from both shoulders and a little pain after doing so several times. my shoulders are cracking and grinding with almost no pain why? i can play and swim but there is crunching sounds

See Orthopedics/PT:: It's possible you injured your shoulders over time/repetition, & now have something like a labral tear. You could have developed arthritis or other shoulder pathology like a rotator cuff tear too. Issues near the shoulder can cause shoulder pain, such as a tear/inflammation of the biceps tendon, or your AC joint (acromioclavicular). Don't force painful positions. Physical therapy can help!