The bottom number is diastolic, top number is systolic. I think there must be something wrong with the machine you're using or the doctor needs to adjust your meds. Your diastolic in the 30's is pretty low. Are you having any symptoms?
I believe the bottom number is due to your beta blocker, it slows down your heart. When I was taking my beta blocker my lowest number was 45(bottom number) I have never seen a number that low. Is your Doctor aware of the reading?
From what I have read, 33 is way out of bounds of normal. There are Drs. who say 70 is the lowest diastolic for most patients. The problem comes because some our b/p meds for the most part lower our diastolic too much. I have that problem too but mine doesn't go to 33.
You need to call your Dr. immediately. I would be calling him or her tonight. I think it is dangerous to have a diastolic that low. Any diastolic lower than 50 is considered hypotension.
If I couldn't get hold of the DR., I would be going to the ER.