Pain with the shoulderblades is usually do to a muscle imbalance. Though your muscles (rhomboids) may be tight, this is usually do to them being too weak. This may also be a postural issue, where the muscles on the front of the body are not in balance with the muscles in back.
Those rhomboids are supposed to stabilize your shoulderblade. If they aren't strong enough your shoulders will be rounded forward. This position places unnecessary stress on the shoulder and may be causing most of your problems.
Taking a break from barbell exercises might help. You might seek help from a trainer knowledgeable about these muscle imbalances. Getting some good quality soft tissue therapy might also help.
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