Certified GKH Gardening Expert
If it was over pruned, there may not be much you can do for it beyond giving it good TLC and hope for the best. Over pruning a plant can send it into shock and that sounds like what may be happening here.
Make sure it is getting enough water and you mat want to try a dose of sugar water to give it a boost (but only do it once as too much will kill it). Fertilize it with a balanced fertilizer.
As a precaution, treat the plant with a fungicide, just to be on teh safe side.