My nails are affected with large white spots and never grow. i've had this condition for over 10 years. no antibiotic treatment has ever helped. cure?

No cure: These are calcium deposits and they are harmless-no antibiotic therapy is needed and 10 years is a bit late to be asking this question. Please consult a dermatologist.

What's the dx?: Unfortunately, unless there is a diagnosis, there is likely little chance to cure whatever you have. The large white spots on the nails are NOT bacterial infections (antibiotics only treat bacterial infections). It may be a fungal infection, autoimmune disease or other non-infectious problem. A dermatology consult and eventual biopsy will likely be needed to secure the diagnosis. Good luck.