There's been a few times where I've noticed several dark bluish spots on the lower half of both legs that look like bruises but I haven't inured them.

There's a condition. called Henoch-Schonlein Purpura (HSP) that can cause bumps & bruises on the shins from leaking of tiny blood vessels called capillaries. Usually the leaking is confined to the skin & goes away own its own. However, HSP can affect other organs, like the kidneys & joints., it's important to see a doctor for an accurate diagnosis & evaluation. Best wishes! Dr. Anne.