I had bumblefoot with one of my road island reds, not a duck, but pretty much the same thing. Can you take a picture of it? Anyways, if it is bumblefoot, you can either call an animal vet that takes chickens, or cut the foot open yourself, like I did. I looked up videos and there are different ways to cut it, so I'd look up videos first if you want to do it yourself. Also, you can use essential oils for the foot, I used it and it really helped. you can soak the foot in Epson salt an hour or two before you or a vet cut the foot. (both the oils and salt clean the infection.) Then you can get some soft gauze, get some Neosporin and PURE tea tree oil and mix it together, put it on the gauze, lay it around the foot with the toes out, then put some self-adhering wrap things around the foot. If you have other ducks or chickens, even, make sure the duck with the bumblefoot stays in a cage out of site from the other ones so it doesn't get picked on and for it to be out of site is for it not to be depressed 24/7. I would keep the duck in a cage until it stops limping almost completely. If you cut it, look up a video. You have to make sure all of the infection comes out. It kinda looks like a fat blob on cooked chicken, lol! anyways, you have to squeeze the swollen part for it to come out. you can also rub an ice cube on the foot to numb it a little, but I wouldn't give the chicken any numbing medicine, because most have an ingredient in it that can KILL them, so I really don't recommend it. Ice cubes work just fine. anyways, don't worry about blood coming out, it will do that no matter what. If you don't want to deal with a squirming duck, wrap it in a blanket, put it upside down in your lap, and put a towel over it's head and talk to it in a soothing voice so it won't freak out. I think you should do it yourself, since it's not too hard at all and it costs way less! Well, good luck on your duck, and any questions I'll answer, or anyone else!