I have strange feeling in my legs. like mild tremor in them is it possible cause of ms or its just sode effect of the prednisolone (omnacortil)?

Likely neither, but: Not clear to me why you are taking a steroid, and mild tremors in legs are very nonspecific, as can be experienced in muscle fatigue after exertion. Prednisolone causes many side effects, but these leg sensations are not characteristic. Ms is a clinical diagnosis compiling many signs, symptoms, and imaging findings, and your complaints are too nonspecific to confirm ms.