The heavy rains are bound to make trees that were planted under marginal conditions suffer. It sounds like some kind of gall on the plant.
Check to be sure that the tree isn't planted
too deep in the ground. Check to be sure that one one applied a chemical fertilizer weed and feed around it - that will kill trees outright.
For the sick tree treatment, let the soil dry out a bit before doing any aeration if it involves using a hose-end aerator.
Check for circling and girdling roots. When was this tree planted? Sometimes if it has been only a year or two and it is still looking pot bound, it is easier to dig it out, untangle some of the wrapped up roots, stake them out and plant it higher (so the root flare is exposed).
Good luck.