My husband's right big toe hurts on the outside of the toe, no ingrown toenails or fractures. it's just the big toe not the joints. what could it be?

Several possibilites: Broken toe bone, dislocated toe bone/joint, gout, bruising are all possible. With his young age, watch closely and if not getting better in a few days, then get evaluated at a local minor er with x-ray. Go sooner if fever, worsening pain, redness develop. Be well.

Bone spur: Bone spur or if his toe is rotated then ground pressure.

Possibly irritation : From a shoe that caused friction and pressure to the skin