Could he have multiple personalities

Caused by drugs? So my ex and I split up and a suspicion of drugs given the circumstances. Every time we fight he will say something and then come back and say something totally different like he never said that before. Like today with this girl he was like “I’m not even seeing her like I was stupid” came back 10 minutes later and said he was and acted like he didn’t say that. He will get angry and call me names and then come back from the bathroom all nice and sweet 2 minutes later like he didn’t remember being that hateful to me. Sometimes he will say things and not remember he even had the whole conversation with me. Then he told me today he knows I’m not trying to take his daughter from him then he comes back and says he thinks i am? It’s all really hard to talk to a person like this and help but also have custody going on. Can drugs cause this disorder?.