We present the recent photometric monitoring of blazar Mrk421, obtained from the Gerostathopouleio Observatoty at University of Athens. Follow-up observations have been performed on this source after a highly energetic flare which occurred on 13 April, 2013. The flare was observed in X- rays by Nustar & Swift and in GeV - TeV gamma-rays by the Fermi satellite and MAGIC/VERITAS telescopes respectively. Continuous photometric monitoring in the optical BVRI bands during 3 months after the flaring activity reveals a quasi-periodic light variation. This is one of the few times that Mrk 421 was observed for such a long period without large observational gaps. We perform Fourier analysis of the almost uninterrupted 3-months-long dataset in order to get insight on the characteristic timescales of the system. We discuss also possible origins of the optical variability by performing cross-correlation analysis of the optical and of the simultaneous X-ray emission detected with XRT onboard the SWIFT orbital satellite.