My dog has a lump under her belly and it pains her some and I think she got stung by bee or something?How would I tell if it is a stinger there in her?

Are you sure something bit her and it is not something worse? I am guessing you would see a redder spot in the middle of the lump if it was a bite.

If your dog is in pain, than take her to the vet. This could become deadly. How long ago did this bite happen? How long has she been in pain for?

You can try and Epsom salt bath, but again, if your dog is in pain, take her to the vet!