Toprol-XL and sooo

I have been having chest pains every afternoon since July 13th, which was right after the doc prescribed me Toprol-XL. I have had SOOO many tests and they can't figure out what the problem is. The chest pains happen in the afternoon while I'm walking, I don't mean walking for exercise I'm talking about walking to the bathroom or just to the other room and my chest feels like it is about to explode. I accidentally quite taking the Toprol for about 5 days. My husband had knocked my pill bottle off the cabinet and out of sight out of mind. Well, Saturday was the first day in over 2 months that I didn't have a chest pain. I didn't have any problems for the 5 days, then I realized that I had been forgetting to take the Toprol and started it back up and the chest pains have come back. Has anyone ever had this same problem?