It sounds a little unusual, but acne tends to appear in clusters and simply by chance, these could all appear on the same side of your face. It’s probably more likely that you are doing something different on that side. Perhaps you sleep on that side? The skin there would be warmer for longer, increasing the sebum produced by your pores and the chances of plugs forming. If that seems feasible, make sure you sleep on a linen or cotton pillow cover, these will allow the air to circulate better and your face won’t get as hot. Poly-cottons and other man-made fabrics will heat up more, and the fibres are more dense, making skin sweat more.
Otherwise, just try to think of what you might do differently on that side; do you cup your head in one hand in meetings or when listening to people? Do you hold a mobile phone to that side of your face? Any kind of helmet that fits around your jaw, could fit more tightly on one side. Anything that makes the skin there warmer or covers up the pores could increase the chances of acne. Treat it as you would any out-break, and in the meantime, try to think of anything you do differently on that side, then switch hands or sleep on your back and see if it makes a difference.