I don’t understand when you all say relapse

I have MS, been experiencing symptoms for a couple of years, been on Kesimpta for a year, taking vitamin d and b12. It just seems my symptoms get progressively worse at a fairly linear pace. Just getting weaker and weaker. Nothing resembles the level of acute symptoms some of you all experience. Anyone else have these types of symptoms? Thankfully its just my left arm and leg so far.