Hi.. Welcome to HEALTHCARE MAGIC.. I have gone through your query and can understand your concerns.. As per your query swollen gum behind two teeth that is appearing like a bubble seems to be due to formation of a gum abscess that can occur due to infection in the area of the gums or can also be due to traumatic injury to the gums in that area with toothbrush bristles or any hard food leading to deeper impaction of the bacteria deep into the gums causing pus formation.. In case if there is any decayed tooth in the area it can also be a dental abscess.. As you are taking Alphamox that contains active ingredient Amoxicillin that is an antibiotic will help in reducing infection but you need to consult a Dentist and get evaluated and he can also do a proper evaluation and can do scaling of the gums followed by continuing antibiotics and painkillers and topical gum pain application for relief.. Do antiseptic mouthwash gargles.. In case of dental abscess root canal treatment of tooth followed by antibiotics and painkillers will help.. Hope this information helps.. Thanks and regards.. Dr.Honey Nandwani Arora.