How do you know if you have an ingrown toenail?

If anyone has had one, please tell me how or if you even knew you had one before an infection started. I’m scared my husband has one that’s trying to become ingrown so I always make him let me push tweezers between the toe and sides of the toenail while he yells in pain. It is the only thing I can think of to keep it from going under the skin. He says it’s just a deep crease in the side of his toe, but that thing goes in there deep (just doesn’t break the skin yet)

Am I causing him unncecessary pain yet kind of amusing… just kidding or does a long side toenail mean potential ingrown?