My dog got stung 5 times a few weeks ago on the stomach when he rolled into the long grass, i took him to the vets and he gave him an anti-inflamatory injection. I put a paste made from bicarbonate of soda and water on it and it drew out the stinger and now he is fine. With it being the tongue, all i can say is piriton or benadryl like Dave says works great, and if your dog likes ice cubes, give him some of them, it will numb the pain while the drugs do there work.