My endodontist said i did not have a gumball nor an abscess nor a swollen cheek. so i didn't need antibiotics for my severe root canal pain. is it true?

Very likely yes: Severe dental pain is not always caused by an infection. The endodontist is being responsible by not placing you on unnecessary antibiotics. Removal of the affected nerve tissue and completion of the root canal procedure should help quell the problem.

True: The pain is caused by the localized inflammation of the pulp tissues inside the tooth. In that case, Ibuprofen will work best against inflammation. If it's severe then he can prescribe you something stronger. Antibiotics will only take care of widespread bacterial infection. It sounds like the tooth was vital (not necrotic) and therefore you should not require antibiotic.

True: Overuse of antibiotics is causing mutations and resistance in bacterial strains. If you do not have signs or symptoms of an infection, just pain then the need for an antibiotic is usually not necessary.

Likely True: Often times teeth require root canal treatment without the presence of an abscess or infection. With no signs of infection, antibiotic treatment may not be necessary.

Re-treat?: most likely this is true, if cone beam imaging is available you could be sure if infection is present or not. If NO infection, NO antibiotic, sometimes root canals fail (to no fault of anyone) sometimes canals are missed (also found on cone beam scan) IF failure or split tooth is the problem, have your tooth removed. If missed canal is the problem, have a retreat. Good luck.

AB is not needed: In most cases, antibiotics are not required after endodontic therapy. They used only when needed and if infection is present. Your endodntist is a great specialist.

True, but: True, but if treatment does not go as well as expected. antibiotics may be added.