Extra sole growth on horses hoof?

My 17year old cob went lame on R fore after being shod. It didnt settle. Had vet out, did xrays, all joints ok but very flat footed confirmation, (pedal bone quite flat to the sole). Was shod with small wedge & equipak gel in sole. Greatly improved after 2 weeks and I was back to daily riding. Then after shoes had been on 4 weeks, she ripped the L fore shoe off, taking some hoof with it. Had a new farrier look at her, who said he wanted to let the hoof grow. She lives out 24/7 and hasnt done anything now for almost 3 weeks. Farrier is due in 2 days, shoes would have been on 7 weeks. Then she has now torn the right for shoe off, taking a small chunk of the outside hoof wall, and already had a chunk missing on the inside which had previously had filler in. There was an obvious bulge in the sole infront of the frog. The vet has re xrayed , which showed no movement in the bones and no signs of laminitis. The bulge could be seen on the xray and appeared to be extra sole. Could it be due to having the wedge/equipak on?