That depends on your tetanus immunisation status. If you are not up to date with your immunisations go and see your GP about it, if you are, then wait and see if it settles. If it continues to swell and becomes more painful / red / hot / swollen you also need to see your doctor. In the meantime a dose of your analgesic of choice is a good idea as is bathing it in warm water. In any case, make sure you get your immunisations up to date and keep them current, the garden is probably the worst source of tetanus bugs it is possible to find. Hope it's soon better.