When my husband had severely sprained his ankle, he had blood pooling/bruising in weird areas, like you're describing. He would have dark purple areas on the bottom of his foot, near his heel. Then it would go away and come back under the arch of his foot. Then that went away and it started bruising around the ankle itself. I do remember his doctor saying that it's related to the severe swelling- there are broken blood vessels from the injury, and depending on the swelling, the loose blood moves and pools depending on activity, how you're standing or how you're elevating it, etc.

It sounds to me like, when you're up and walking on it, it's probably getting more swollen than, say, if you were home and have it up (or sleeping at night, where you're lying down). And the swelling from being up on it is making the blood pool. What you need to do is stay off it as much as possible. Elevate it when you can, and ice the area to try to keep the swelling down. If your toe is broken, the ongoing swelling (and going between swelling and not) can affect how it heals. It can move the bone pieces around, which could make it take longer to heal, and if it never aligns correctly, it won't heal straight.

Tape it to it's neighbor and stay off it!