do you have a salinity test meter or kit .You may have added to much salt that could be causing the ulcers you speak of .I'm really not sure because I always test before i add anything . Can you post a pic of your pond .You may be adding to many items all at one time .They are fighting each other .Maybe just do the water changes .Salt or no salt is not going to change things .Over filter the water .I use quilt batting to take all the fine stuff out .I put it on top of my filter and try to make sure the water runs through it .Maybe super filtering the stuff out will help , clean the quilt batting often also . I'm just not sure .Have you added any thing new besides the treatments you said or could there be something dead in the pond somewhere you can't see it .Something is wrong thats for sure .Waterbug seems to know more about water conditions ,but I guess I'm just not sure since I have really never went through what you are going through and I guess it is really upsetting you and I know it would me . Something has to work .Don't feed the fish ,I know it sounds crawl but it is for there own good .I have not fed my fish for over a week because ammonia levels went up ,actually it has been 8 days and level went down but is not stable yet .