Sudden tight pains in rib cage and across middle of back?

Tightness c/w muscle: contraction, which (if enough & sustained) can become painful. All our muscles (heart muscle more so; especially inner walls nearest chambers) ↓ blood flow during contraction. The contraction pressure opposes & ↓es blood flow into muscles via arteries & capillaries while ↑es flow outward into the veins. Thus sustained contractions induces ischemia & (if long enough) contractions become painful.

Thanks: For the post but your question is unclear . Trial of OTC pain reliever or get evaluated if no response or for diagnosis