That's a big bumble but I think you should still use the Epsom salt soaks dry and use the corn/callus or clear iodine on it soak , another reason I like the clear iodine is I can paint top and bottom and I don't have to worry about getting the iodine on non bumble skin like with the corn/callus remover. So soak dry and treat every other day for at least 3 times then post back with pics. after that you may be able to go every 3 days with treatments. This is how I used it with my hen. I used q tips to really get the iodine all over bumble top and bottom. Works alot better than that lil thing they put into the bottles. Keep him on clean shaving or towels till it heals. I've never had one that large so this is new territory to me, So far non of my water fowl have had bumble on a few of my chickens. I think it's best to try this approach before surgery, now if you have a vet willing to do the surgery and you feel that's the way you want to go then by all means do.