Another way to treat this is to file your nail across the large flat surface of the nail. This is to make the nail thinner in the centre of your toe than at the sides. This will of course weaken the cantre of the nail so that any new growth tends towards the middle of the nail rather than the sides. That will help to prevent new growth 'digging in' at the sides.
If you try this make sure to cut a small 'V' shaped nick at the top centre of your nail. This will help prevent the weakened nail from splitting.
It's a painful condition but it is curable with the above non-surgical technique.