You are holding your breath each time you draw the bow, wake up. The cracks are there because you have protected the knot and the tree also protected it causing your bow to twist in the limb in a very short section; always remember wood grows so the tree survives not your bow. C.A. glue will work not preferred, only with sinew wrap added. Might consider silk back with sinew wraps as a permanent patch. Half measures result in half a$$ work. Each bowyer makes hundreds of decisions each bow, listen to to the wood, and yourself you Know the way.