I have had a bad taste in my mouth for months and no one can figure out what is causing it. I have been to the dentist and had an old filling removed and a crown put on then I had to have a root canal then several months later I thought the crown was the problem so I had my dentist cut the new crown off. No change in the taste in my mouth. Last week I saw the PA and he prescribed Nystatin thinking I might have thrush . I have also been taking omeprazole because the doctor thought it might be from acid reflux. I gave also taken a course of ranitidine and Zantac for the same reason. I have seen an ENT doctor who told me I had dry mouth and drink more water! Nothing is working and I don t know what the next step should be.