Fell hit knee cap on wooden stair. Not bruised at sight but on left side of knee and hurts down front of leg and throbs at top of foot. Serious?

Tough to say. It is difficult to tell on the internet. Are you on blood thinners? It is possible you have developed a hematoma or pinched a nerve. Most likely, the pain is referred to your foot and will resolve. If you can't bear weight, can't move your foot or have a loss of sensation see a doctor tonight.

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I twisted my rt knee bowling. It hurts below the knee cap and behind the knee with pain generating up the thigh and down to foot, bruise under knee?

See medical provider. A twisting injury to your knee can be a number of things from a sprain to arthritis flair up or cartilage tearing. See a medical provider for an evaluation with X-rays. You may also need an MRI to look for ligament or cartilage tearing. Read more...