You go to the ER for help and they don't tell you why? Do they fix it by cauterizing? Theres any number of reasons for nosebleeds - from simple dryness, drugs, too much picking, burst blood vessel, brain aneurism...... where I work its very dry, workers use vaseline to prevent nose bleeds.
When you go to the ER have they run a complete blood count? You could be having nosebleeds due to many metabolic issues: anaemia, and leukaemia from one end to the other. You need to see your primary care physician. Good luck. I hope you are well.