Many things could be causing this, and we'll go through a few of them. After that, you'll need to take him into see an Avian Vet in your driving area as this could be infection since foot is swollen.You'll probably need to take him in anyway as sounds like he does have an infection.
First, what kind of perches is he on? Parrots have to be kept of natural wood branches so their feet and legs have some relief from sitting on a wooden dowel or some other perch that is the same diameter all the way across. Tracie has a list of safe wood out here, and the natural branch perches can be found on the internet and in pet stores with the hardware already installed. Your Amazon would need perches from 1.5 to 2", as the branches are not same diameter all way across.
Second, what kind of diet is he on? Parrots need to be eating a majority of their diet in organic pellets like Harrisons though Tracie also has a few other kinds as well. The organic pellets are the best because they have no preservatives, dyes or pesticide/fertilizer residue. The cost may look to be a little more, and that is made up for in less vet bills because bird is healthy. All seed diets cause problems like fatty liver disease, gout and other organic problems because they are no where close to a healthy diet.
Third is that this is an infection which could be caused by something like a bacteria or could even be gout caused by poor kidney function. Be sure and have Avian Vet do bloodwork to rule out problems with Kidneys and Liver plus a CBC to see if white blood cells are in large number indicating infection. Also ask for a collar for your bird to keep him from biting on his leg until you can get to the bottom of this. Make sure food is put where bird can bend over and put the collar over food and water dishes so he can eat and drink similar to what we have to do when dogs are in the collars.
Also, let us know what you did and what the Avian Vet found or did not find, as we are concerned about your bird.
Thanks for writing and we hope that everything works out for your bird's highest and best good.
