What Could Cause Erratic BP While Being On Candesartan Cilextil With Hydrochlorothiazide?

i have been taking Candesartan cilexetil 16mg with hydrochlorothiazide12.5 mg for 10 years with good results... i am in India taking the same meds but made in India, for the last month.... very poor results... increased dose to bd, sometimes taken 24mg CAndesartan but still very erratic and elevated bp this am 200/120 last dose 10hours prior... with 24mg this am... bo still 150/90