A variational formalism for the calculation of the binding energies of hydrogenic donors in a parabolic diluted magnetic semiconductor quantum dot is discussed. Results are obtained for Cd $_{1-x_{in}}$ Mn $_{x_{in}}$ Te/Cd $_{1-x_{out}}$ Mn $_{x_{out}}$ Te structures as a function of the dot radius in the presence of external magnetic and electric fields applied along the growth axis. The donor binding energies are computed for different field strengths and for different dot radii. While the variation of impurity binding energy with dot radii and electric field are as expected, the polarizability values enhance in a magnetic field. However, for certain values of dot radii and in intense magnetic fields the polarizability variation is anomalous. This variation of polarizability is different from non- magnetic quantum well structures. Spin polaronic shifts are estimated using a mean field theory. The results show that the spin polaronic shift increases with magnetic field and decreases as the electric field and dot radius increase.