Avoid super sweet, hot cold and spicy foods in order not to stimulate the tooth.
Just stay away from eating hard crunchy foods tonight. Try a little rinsing with warm salt water and take some Advil or Ibuprofen prior to alleviate the discomfort tomorrow. You should be fine and feel a lot better after the root canal is completed.
Hope this helps,
Jossi Stokes, DDS
Brett E. Gilbert, D.D.S.