The swelling under the knee cap sounds like what is known as a pre-patellar bursa or more popularly known as housemaid's knee. The bursa used to commonly occur in housemaid's knees because they had to kneel on the floor to clean it.
A bursa is a small sac on a joint containing fluid. When an abnormal amount of fluid gets collected, either due to injury or inflammation or spontaneuosly, it forms a bump under the skin. In your case, it is likely that there has some amount of mild trauma to the knee while riding your motocycle.
In many people, the bursa may remain for years without causing any symptoms. But if the bursa becomes bigger and painful, it is due to infection.
You do need to consult a doctor for an examination. Meanwhile you can apply an ice pack over the bump for 10 minutes thrice a day and take Motrin or Aleve 500mg thrice a day to bring down inflammation, if any. Apply an ACE or other elastic bandage over the bump to prevent excessive movement. Keep the leg at rest and elevated as far as possible.
Bursitis are typically treated with cortisone injections and draining. But if these treatment procedures fail, you will need to undergo surgery to remove the entire bursa.
Nowadays, this is a relatively simple procedure and can even be done by pinhole surgery.
The numbness in the tip of your index finger could be due to pressure over the nerve while riding the bike. In most cases of this type the sensation returns in time, but you can get it checked out by your doctor.
I hope this helps.
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