I had acute bronchitis a month ago and was on antibiotics. When I stopped antibiotics the symptoms return?

Possibilities... Acute bronchitis is due to an infection of the airways. It is possible that you are now experiencing bronchospasm post-infection, which can have some of the same symptoms. If you have ever smoked, it is possible you actually have chronic bronchitis, a form of copd. For proper diagnosis and treatment, see your doctor again so your symptoms can be re-evaluated.
Several reasons. It is possible that you are experiencing a secondary infection, reactivity of the airways, or that you have an underlying condition that predisposes you to recurrent infections. Other reasons for this to occur include two separate and unrelated infections and resistance to the antibiotic prescribed. Your physician may order additional testing to determine the cause.