I be you 10p I know exactly what was wrong with Adam Proudlock. He was cutting his toenails wrong. I had exactly the same problem. If you cut your big toe nail straight across and wear tight shoes or boots, then the edge/corner of the nail digs into the flesh and at first it gets sore and then it turns septic. Best thing to do to stop this is to cut each corner off diagonally as deep as possible down the toe and then there's nothing to dig into your flesh. I think that's what an operation for an ingrowing toenail does anyway (but more extreme).
It works for me anyhow. I've had no trouble since I started doing this.