An innovative theoretical approach for deeper understanding of the ultrafast spectroscopy experiments through solution of the Boltzmann transport equation coupled with various nonlinear scattering mechanisms, overcoming the limitations offered by DFT, RT-TDDFT and molecular based methods, is reported. A clear advantage of the real-time approach is that it does not make a priori assumptions about specific scattering, relaxation mechanisms and has capabilities to capture the full real-time carrier's dynamics, including the superposition of all electron--electron, electron-lattice and electron--phonon scatterings etc. No such method with advances in theoretical treatments to explain ultrafast spectroscopy has been reported previously as per the author's knowledge.