People usually do not "lose" their asthma. It is likely that for any of a number of reasons you are again experiencing some asthma symptoms. This is not uncommon. I would suggest seeing your family doctor and having a lung function test to determine if this is the case or not. On the basis of an examination and lung function test, appropriate therapy can be given to control your symptoms.
Congratulations on being smoke free for 5 years. You have made a wise decision to stop smoking! You may want to look at our Quit Smoking Topic Center at http://www.nationaljewish.org/topic/smoking_cessation.html for ways to help you stay smoke free.