You can go ahead for M.Sc in Comuter Science after B.Sc ( computers). This post - graduate degree will enhance your job-prospect in the field of Information- technology.
As far as Mathematics is concerned, it is an important tool where there would be frequent use of Differential and Integral Calculas, Vector Algebra, Matrix and Differential Equation etc in course of computing datas. Without the application of Mathematics, this field cannot be conceived of. Hence, it would be worthwhile to have a sound concept in Mathematics to expertise the different tools applicable in the domain of computers. Once, you are proficient in Mathematics, the programming will be easier for you and frequent use of Mathematical - application would not allow you to forget your concept in Mathematics.