Toprol-XL and tht

Since a few days prior to Christmas I have been experiencing constant chest pain about 4 inches below my collar bone. I've been on Toprol 50mg for almost a year and it has helped some with my high BP. I have no idea if toprol is the medication tht may be causing this pain or if it is due to something else. I would describe it as dull (maybe a 2 on a pain scale of 1-10). Worried, as I am only 23, I went to the ER and the ER doc couldn't pinpoint the problem after doing blood work, ekg, and a chest x-ray. I forgot to ask him if the med could be causing such a side effect, but he did know I was on toprol. The pain doesn't seem to be cardiac related as I just got done running 3.5 miles and the pain seems about the same. Again, I don't know if left-sided chest pain could be a side effect of Toprol, but I would certainly like to know if anyone has experienced these symptoms while on the med or can confirm this possibility. Thanks guys and gals!!