You should seek medical care - either at the ER or your doctor. You'll be sorry later if you neglect any injuries to the ankles, knees or spine.
However, check your medical insurance coverage. If you have a PPO with a high deductible and your doctor has to send you out to a lab for x-rays/tests, the cost will be applied toward your 2005 deductible. If you go to the ER - you'll have a higher co-pay, but any tests they do on site will be covered.