  In pump-probe spectroscopies, THz pulses are used to quench a system, which
is subsequently probed by either a THz or optical pulse. In contrast,
third-harmonic generation experiments employ a single multicycle driving pulse
and measure the induced third harmonic. In this work, we analyze a spectroscopy
setup where both a quench and a drive are applied and two-dimensional spectra
as a function of time and quench-drive delay are recorded. We calculate the
time evolution of the nonlinear current generated in the superconductor within
an Anderson-pseudospin framework and characterize all experimental signatures
using a quasiequilibrium approach. We analyze the superconducting response in
Fourier space with respect to both the frequencies corresponding to the real
time and the quench-drive delay time. In particular, we show the presence of a
transient modulation of higher harmonics, induced by a wave mixing process of
the drive with the quench pulse, which probes both quasiparticle and collective
excitations of the superconducting condensate.
