ASD - behaviour improved but increased stimming

[amunt]

4 year old Ds’ behaviour and attending skills have improved hugely over the last few months with various strategies. He never had any visible stims, but recently has developed quite a few – head shaking while walking, repeated counting, hands down his trousers, touching his face etc.. I assume that his oppositional behaviour was a kind of stim before and these have replaced it. Does anyone have experience of this/advice?
Thanks