Tooth pain

Ok so I went to go get fillings done. The doctor said that it looked like I needed a root canal because of how deep the hole was. She asked me did it hurt me and I said yes. She then said she’s just going to fill the hole as a filling and for me to come back if it bothers me. Well it hurts 10 times more now that she filled it. I don’t understand why she would fill it if I needed a root canal 🤦🏽‍♀️ what can I do?