If you have recently traumatised the nail either through kicking your toe or dropping something heavy on your toe there is a chance that you have merely damaged the nail / nail bed and may not need to treat a fungal nail infection (with that said, it may need podiatry treatment to prevent other complications). If there is no history of trauma however, it is likely you will need to either begin fungal nail treatment or visit with your podiatrist for an assessment and for management.
Please be advised that if you plan on treating it conservatively yourself – antifungal nail lacquers are limited in their capacity to penetrate deep into the nail when the fungus has burrowed into the deeper layers of nail cells. This means your treatment effect can be limited and your infection is at risk of worsening. This is particularly true if your nail is thickened.
Nb. If you are planning on treating it conservatively yourself, we highly recommend that you consider a professional assessment beforehand to confirm that there is actually an infection present and you’re not wasting your efforts.