Dear Dr. Roach: I’m a 68-year-old woman in good medical/physical condition.

I run three times a week and work out with weights regularly. The only medicine I take is bioidentical hormones.

Recently, the side of my foot near my baby toe felt sore as if, when I walked, I was stepping on a small pebble. It’s not really painful, but annoying.

This started about midday and continued throughout the day. The following morning, I woke to find the same part of my foot darkly discolored as if I’d had a bad injury.

The bruised covered about a quarter of my foot. By the next morning, the discoloration had completely resolved. There was no other pain.

What caused this — perhaps a blood clot? Could this be a warning sign of something more serious?

The only other time this happened was to my big toe a few years ago, and then it was exactly the same, some soreness, the bruised appearance and then complete resolution the following day. — M. J.M.

Answer: A bruise is the usual term for what medical professionals call a hematoma, a collection of blood located outside the blood vessel. I believe that’s exactly what you had. Runners and other active people get trauma to their feet, and a small blood vessel can break, letting blood collect inside the tissues.

Gravity usually pulls the blood down, often to the skin, where the discoloration can be noticed. Your bruise resolved quickly, within a day, suggesting that the blood internally was not a lot of volume, but was spread out over a large area.

I do not suspect a blood clot in a vein. That usually shows up with swelling, since the blood isn’t being drained properly and fluid literally backs up behind the blockage.

Estradiol, the bioidentical major human estrogen, does predispose a person to clotting, but even so, what happened to you still doesn’t sound like a clot.

Discoloration is unusual, although sometimes a clot can be felt as a hardness in the blood vessel.