Multiple time origins in LAMMPS

Hello everyone
I am trying to calculate the MSD + diffusion coefficient for very small diffusion events, for me the c_msd[4] and v_twopoint(that are MSD and slope of msd =Diff coeff[D] respectively) in the logfile for Diff coefficient calculation make sense but the v_fitslope (fitted line in the msd +slope =D) don’t make sense as it is very small e.g. 500000[step] 1194[temp] 0.053140182[msd] 0.00010628036[v_twopoint] -4.2251535e-07[v_fitslope]. I think the possible reason could be the signle time origin for our MD.
can you suggest anyother reason or suggest me how i can implement multiple time origins in my run ?
Irslan Ullah Ashraf