Hello! Hi, I had gone through your question and as you describe it seems to be an extended infection in the location you prescribe. Having a white bump and gum around your tooth and also tasting nasty seems most propably as an abszess. An abszess is an capsulated tissue fusion and pus accumulation with surrounding abscess membrane (in non-preformed body cavity). In your case you should start antibiotics such as penicillin and visit your Dentist. In any case a drainage is indicated so that the pus can flow out. Because of the abszess membrane the antibiotics don t have an effect without a proper drain. In this case its important to know if its just located in your soft tissue or is deep in the dental root with affection of the mandible (bone). An X-ray imaging of your dental panorama visualizes especially the roots. Of course if its possible terminate it sooner. The second case of such an infection is a parotitis ( infection of salivary glands) It can be seen if the swallowing is on the outside chick as well. In this case the diagnostic is through an ultrasound of this region. In case of that antibiotics should be taken, drinking a lot of and citrus fruits help. I wish you good health.