1.23: Equation of a curve from a trigonometric second derivative

A curve is such that $\dfrac{\mathrm{d}^{2}y}{\mathrm{d}x^{2}} = 2\sin\left(x + \dfrac{\pi}{3}\right)$. Given that the curve has a gradient of $5$ at the point $\left(\dfrac{\pi}{3}, \dfrac{5\pi}{3}\right)$, find the equation of the curve.