I have an inflamed bubble of flesh in my gums. it is the diameter of 0.5 centimeter. no pain. just noticed it. no history. practice good oral hygiene?

See a dentist: It is possible that you had a minor injury that caused that. If if remains painless and goes away in a couple of days you should be fine. But if it lasts you should see a dentist - even if it doesn't hurt.

Gum swelling: So many possibilities, most of which are self limiting and benign. If it is fully healed and gone in 2 weeks, no additional treatment is needed. If still present at the 2 week mark, please see your Dentist for an examination to determine cause and appropriate treatment.