You don't have to worry , you have to do something. Visit a dentist and have an Xr taken to see the root of the tooth for possible infection. After an acute abscess it is quite possible for the infection to become chronic, meaning you still have an infection without having discomfort. If it is determined that this is the case having root canal done is the way to go if you don't want to loose the tooth. If the chronic infection is not treated it can cause root resorption and/or resorption of the bone around the root of the tooth.
In some cases the acute infection can subside after the antibiotic and and actually heal. If the nerve of the tooth survive its all good, and if it does not it may die and the canal calcify. The only symptom in this cases is darkening of the tooth.