Dipole Oscillation Frequency in Electric Fields

A rigid dipole undergoes a simple harmonic motion about its centre in the presence of an electric field $\vec{E}_{1}=E_{0}\hat{x}$. If another electric field $\vec{E}_{2}=2E_{0}(\hat{y}+\hat{z})$ is introduced to the system, what will be the percentage change in the frequency of the oscillation (approximate) ?