I feel like my BF is wanting to fight/looking for things to fight about

Him and I are pretty serious and have talked about marriage and kids and everything, but the past week it seems like he is LOOKING for things to fight about. Almost like he wants to fight. Things that don’t even matter and have already been talked about but he’s turning into a huge deal. We’ve been fighting on and off for the last 4 days on various subjects. We get over it, everything is fine and then he finds something else to fight about. Has this ever happened to you? I don’t know what to do / what to say to him.