Back pain and "grinding" noise between shoulder blades

Hello! I have been taking care of children for the past 7 years. Constant holding and picking them up is taking a toll on me. Backache is an every day thing. My posture has never been great but it has gotten worse. I constantly try to remind myself to stand straight. So when i pull my shoulders back i hear this grinding noise or a series of pops right in between my shoulder blades. A few weeks ago i discovered what appears to be a vertebrae that is not aligned with the rest between my shoulder blades. What could this be?

Thanks a lot for all your help!

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