Hello,
Thank you for your query at DoctorSpring.com
I understand your concern.
Will you be able to attach an image of your toenails?
It can happen due to a long term fungal or local infection of the nails.
I can guide you once I see how it looks like.
Regards.

Hello,
In absence of any kind of injury, this seems to be due to fungal infection.
I will advise you to apply Clotrimazole ointment around the toes, and control the infection first. It commonly happens in diabetics with poor control of sugar.
Once the infection in controlled you can get it excised by a general surgeon and new nails will form over the nail bed. That will lead to a stronger nail. Then if good hygiene is maintained this problem won't arise again.
Regards.