We have a live oak in the Austin area. It's been in the ground for about 12 years. Last August, about one-third to one-half of the leaves turned brown and fell off. Our arborist thought it was a drought stress issue and we didn't see any signs of disease or borers or pests. He thought at the time that it was a watering issue. This May, we had new leaf growth but it only got about half of previous foliage. Then we started noticing some splits in the bark, which have continued to get worse. Our arborist thought it was borers and we treated it with injectors, but we still never saw any shot holes or clear signs of borers. In many places, the loose bark is now being pushed outward by granular type growth underneath. I've included photos. Any idea what's going on?