B.L.
So sorry to hear about this- I know how it feels to helplessly watch while your child is in pain. I had the same problem a while back. I bought some pure CLOVE oil from a herbal shop, and applied it to my baby's gums- and it seemed to help a lot. Also, being a natural product, there are no side-effects. Please try and see if this helps your grandson at all.
http://www.SmilingSnaps.com/SamplesReviews.html