My Doctor Put Me On 25mg. Of Hydrochlorothiazide (i Have

my Doctor put me on 25mg. of hydrochlorothiazide (i have had high b/p for years and take two other medications for it; doctor says I have to be on hydrochlorothiazide, by law, because of those two meds. Last year, with ONE b/p reading in the office, he decided to put me on 25mg. (up from 12.5mg I had take for eight to ten years). I have had persistent cough about a month after starting the 25mg. and cannot get rid of it after a year. On my yearly blood tests, my potassium is now low. I want to go back to 12.5mg., but I don't think he will allow it.