This is a very important point, and failing to follow it will make the situation worse:
Do not apply heat to the affected area! A heating pad, a compress, or sleeping on the affected cheek can cause the inflammation to progress to a purulent stage, leading to the development of swelling (abscess).
Do not self-prescribe antibiotics. Unsupervised use of antibiotics “masks” the clinical picture and does not solve the problem, since the pus from the root canals will not go anywhere.
Do not pick at the tooth with sharp objects. You risk introducing a secondary infection or breaking the tooth’s enamel.
Do not take aspirin by applying it to the gums. This will cause a chemical burn to the mucous membrane, adding pain from the wound to the toothache.