The stinger may still be in the bite. An old fashioned remedy is to place mud over the bite which is supposed to draw the stinger out as well as sooth the bite. Another is to make a paste of baking soda and water and place over the wound.
Sounds crazy, but moistened tobacco. If you can find someone who smokes borrow a little of the tobacco add a little water, just enough to make it stick together and place it on the sting. It will draw out the sting I promise.