Lately my chest has been tightening up when i take deep breaths in. what does this mean ?

Costochondritis: The most common cause of chest tightening is inflammation of the muscles that are between your ribs, a condition called costochondritis. This could happen as a result of cold, viral infection, heavy lifting, etc. I suggest taking some over the counter anti-inflammatories to see if it resolves it. If not and it persists, then you might want to see a doctor for eval.