how long until I feel better

I have been off of atenolol for 10 days due to cough, chest tightness, shortness of breath, leg pain and fatigue and depression. Anyway, the depression seems to be lifting and my energy seems to be getting better but the chest stuff is not getting better. My doc just keeps saying I have asthma, but I never felt like this before this med. I was taking 50 mg for about 5 months. I was wondering how ling does this stuff take to come out of my system. I'm starting to get scared b/c of the shortness of breath. Please help thanks