Toenail Infection 
When persons who have thick, tough toenails cut their nails in a convex curve, as the nails grow the edges may start to penetrate the skin and cut the soft tissue. This may lead to inflammation, swelling, pain, and possible infection. Generally, the nails of vata and kapha individuals grow stronger, so they are more prone to toenail infection. Shoes that are too tight can create pressure on the nails, also potentially leading to toenail infection.
The long-term solution is simply to cut the nail straight across, or with a slightly half-moon shape (a concave curve). That allows the nail to grow straight forward instead of into the skin at the sides.
If the nails have already begun to grow under the skin, soak your foot in warm water to soften the nails. When the nails are soft, clean them and apply some tea tree oil mixed half and half with neem oil under the nail. Then cut the nail straight across.
To prevent recurrences, wear soft shoes that are not tight, and cut the nails straight across or in a shallow half-moon shape.