Had a unilateral pars fracture go misdiagnosed since august 13' couple weeks ago started hurting in left side too. pain is a lot worse. can it heal?

Yes: Actually, only a small percentage (10-25%) probably actually heal in terms of bone-to-bone union. However, many heal with a fibrous (non-bony) union. Also, many that do not heal still stop causing pain. The large majority of patients with acute pars injuries are pain-free within 6 months, whether there is full healing or not. A brace that prevents extension can help reduce pain.

A late diagnosis.: If DX earlier u would have had a better chance 2 heal with bracing ; activity modification. Also u need 2 b sure this isn't a developmental defect. Unilateral lesions r more likely 2 heal than bilateral, as there is some built in stability. This late b sure u r cing a spine surgeon.