Was the "LBS/Fitter" the same one who did the pro fit that worked well for you for 6 months? If not, put your Arione back on the way it was and go back to the first fitter who should be able to consider what he/she did for you before. Your body or riding have evolved, and your fit needs to change accordingly. If you get a new fitter at this time that person needs to start all over. The person who knows your fit will not have to start over, just consider how you've changed, if he or she has kept records. Most good fitters do so.

Standard LBS practice is "sell him another saddle." I don't think they selected well, since you are not complaining about perineal pain or pinching, or numbness. Cutouts are mainly for those issues.

Similarly the recommendation for more arch in the saddle. Why? It may move pressure from the sit bones, but not to anywhere else that it should be.