I Fell Down Some Steps 8 Days Ago Resulting In

I fell down some steps 8 days ago resulting in severe bruising and pain, but no broken bones. I landed on my head and shoulders, but was injured front, back, crown of head, and sides. CT scan at ER showed no intra cranial bleed or hairline cracks. I am 76 and take coumadin. Yesterday I noticed pain in the area of my right knee when walking. Have been tired and fall asleep throughout day and night. Although right knee hurts when walking, it has been 8 days since the fall and I wonder whether the new pain could be a delayed reaction. If so, what should be done, if anything. Please advise. Thank you.