Yeah that could be the explanation, although I've read proviron is only mildly suppressive of the HPTA.The reason he felt miserable while taking the DHT wasn't really from the DHT itself. It was due to the shutdown of of gonadotropin synthesis. So, while he had reasonable or even high levels of DHT, his testicular steroidogenesis was reduced and he was deficient in every other steroid made starting from pregnenolone down each unique steroidogenic pathway.
This period of time where "things felt off" was due to having simultaneously low steroidogenesis and, now, no DHT since he ceased using that. During that period is where the HPTA readjusts and begins producing gonadotropins. As steroidogenesis returns, the hope is that AR expression is lowered and 5AR expression is restored and it seems like that's what happened for him.