High Blood Pressure

[AMV2069]

Hello, My mother is 56 old. She is on Atenolol 25mg, Analetin 5mg(not sure of the spelling), and Zantac (She used to be on Nexuim). Within the last few month she is been having accelerating blood pressure in the evenings. Her pressure goes from 105/65 to 185/150 in minutes. It happens randomly 3-5 times a week usually between 6-10PM. Her pulse could anywhere from 65-95 during the attacks. Her doctor gave Clonidine to control the pressure during the attacks. The attacks have been increasing in frequency.
She had CT scan of her kidneys and adrenal glands and they were clean.
It is a mystery to us and her doctors. I am afraid if could a condition is getting worse everyday and could be too late by the time we find out the real condition.
If anyone has come across such a condition or has any suggestions, we would appreciate your help.