Hi. I had fungal nails for years then laser therapy cleared

Hi. I had fungal nails for years then laser therapy cleared it up over 2yrs ago. They recovered well. But I'm now experiencing chronic oncholysis resulting in toenails being really damaged. I don't have any debris etc to indicate fungus has returned & I treated for a while but stopped as I felt it wasn't helping. I think my toes got worse after a 3 week period of nail polish 4 months ago but now they just seem to have deteriorated. Any ideas what other conditions would more likely cause this?