welcome to HCM!
It's normal for a toenail to come loose and fall off after an injury
to the toe. However, if you haven't injured your nail, a loose nail is often caused by over-manicuring the nails and cleaning under the nails with a sharp object.
it may be a sign of a fungal nail infection
which you think its not however you should get a scrape smear examined for fungus
an overactive thyroid
, poor circulation, or nail cosmetics may be a cause
A loose nail should be cut back to where it is detached in order to allow the nail to become reattached as it grows. clean your nails with anything other than a soft nail brush.
hope this is helpful.take care!