Sounds like Ips beetles. Once the trees get stressed from drought, the Ips beetle senses it and attacks the weakest trees. Ips is a bark beetle that kills the tree by tunneling in the inner bark and girdling the tree. If it is a bark beetle, you should see nickel sizes globs of pine pitch called pitch tubes where the beetle has bored into the tree and the tree responded by extruding pitch in an attempt to repel the beetle. Look up the stem to see if there are any pitch tubes.
Here is an article with some info about Ips beetles. There are some pictures so you can get an idea what a pitch tube looks like. Unfortunately, there is not much at all that you can do about it. You are right about needing rain. The last two years have been disastrous in Central GA. I am losing some to Ips just as you probably are.