Blister on gums can be there because of infected tooth present. Infection must have reached the dental pulp which has nerve and have caused pain and bump on gums. Blister on gums can also occur because of gingival or periodontal abscess present. If infection has reached nerve, then root canal treatment is required for the tooth. In root canal treatment, infectious necrotic portion of tooth is removed and is replaced with filling material. Pain in tooth, swelling and tenderness of gums, recurring or persistent bump on gums are symptoms which suggest that root canal treatment is required. Infection will not go till you get treatment done for your infected tooth. If there is gingival or periodontal abscess present, then treatment is required for it. If you don’t have insurance, then you can visit a dental school where treatment is done by dental students under supervision of experienced dentists or can look for free dental clinics around you. By the time you visit a dentist, you can take otc pain med for some relief. You can avoid eating from that side of mouth and maintain good oral hygiene. For more info on signs and symptoms of root canal therapy, refer to…….    http://www.identalhub.com/article_signs-and-symptoms-of-root-canal-therapy-104.aspx