When i bend over while standing up, i have sudden/sharp back pain in my spine between the lower end of my shoulder blades. possibilities?

Low back pain: Most likely causes are sprain and strain. Given your age, costochondritis is also a possibility.Less likely are herniated discs, since you don't describe a referred or neurogenic type of problem.

A couple of thoughts: Sharp pain at the lower edge of the shoulder blades aggravated by bending over may be caused by thoracic disc inj./vertebral dysftn/nerve compression/ligament inj or rib dysfunction, usually.X-rays will rarely reveal the cause.MRI may show disc inj., but only a good phys. incl. osteopathic hands-on exam will likely find the other causes.Care may then incl. manipulation/prolotherapy/surg/meds, etc.