As you can see from the image a vertical portion of my wall (a wood beam) has developed this vertical bubbling where the paint is being rejected. It spans from the ceiling to floor. First thing I thought of was water damage, but as I chip away at the paint and get to the wood it doesn't seem like there is obvious damage, but maybe it's further in the wood? Any other reasons this is happening? Do I simply keep chipping away, then slab a bit of spackle on the plaster and repaint?