That happens to me. I despise coffee but used to down it to "go" and even that quit on me. I fast like once or twice a year and I can't even use "senna tea" anymore because it doesn't work.
Try Oxypowder . It's the only product my system has never gotten "used to" and quit working. And I have a thyroid problem. I don't take Oxypowder much anymore but when I do, it still works and it's been 2 years. Money back guarantee if you buy it on their website too.