My last name is skicewicz
If the root of your surname is "Skic" it probably is in its correct and unchanged form. In that group you'll find surnames like (Skic, Skica, Skicaj, Skicak, Skiciak, Skiciński, Skiciuk, Skicki, Skiczak, Skiczek, Skiczewski, Skiczko, Skiczuk, Skiczyński), however no Skicewicz. So if you were looking through some database of surnames and can't find yours, having doubts now it is still possible it remained in its unchanged form however rare it may be and don't let the fact that it doesn't figure on some database of surnames steer you in the wrong direction. The lack of its presents on some list does not necessarily mean that it never existed in that form at some time in the past. Given that the root "Skic" means (someone active, of vigorous or hyper nature) and the suffix "ewicz" (son of) the X-ewicz is "son of X" in English. It all points to its legit unchanged form. There's no "Skciewicz" either but that sounds unnatural to me so I would exclude this possibility. Unless you really find yourself at a dead end in your research I would stick to what you have in front of you and what you know before contemplating any possibility of it ever being changed.