He’s old enough at this point, it could genuinely be his mind going, causing so much flip flopping. OTOH, him having spent his life used to calling shots and people listening, it may be breaking his brain a bit that he is currently holding one of the most powerful positions in history and Iran is not only not doing what he demands, they’re actively destroying components of what makes that position powerful in the first place with no end in sight. He is getting humiliated on a large scale and for someone like him whose life revolves around ego, it’s gotta hurt; that is, if he’s still coherent enough mentally to comprehend it properly.

Though this is also assuming any sort of accuracy to the information he’s getting. He could be insulated from some of the reports and reacting to whatever he hears from advisors or Fox News without any kind of comprehensive picture given to him on what’s going on.

Whatever the cause, the character of it looks very tantrum-like.