Hello Doctor, My Child Was First Given Pentavac, Then We

hello doctor,
my child was first given pentavac, then we gave pentaxim two dozes(which includes a booster dose which was given one year after the speculated time) as it does not have pain again now we had to give pentavac due to the non availablity of pentaxim, i heard that it is always preferred a shift to painless from painful but not vice-versa, kindly clarify me what are the demerrits of 1)shifting painless to painful 2)giving a dose after the speculated time.. kindly help. Thank you