Should I wait or Confront things?

I've been dating this person for 2 months. The first half was great but the second is proving to be extremely lackluster. He bails on the dates we plan and we usually have only an hour or two to hang out when things actually work. We also don't communicate as much through texts. He claimed that he had been busy preparing for a concert which he just came back from, but I still don't think he'd be on the run to the point where we could barely see each other. Anyway, I texted him when he came back and we got into a small argument. He basically rudely turned down a date that we had planned (right before I'm heading off to Mexico for a week). I'm guessing he's suffering from exhaustion and a hangover. He hasn't messaged me in a day. I've tried talking things out with him through text but it never seems to resolve anything...

My question is this: Should I wait for a response on his part (this will really stress me out in the meantime) or should I confront things on Thursday (the day before I leave) and try to be more assertive? I don't feel I've been assertive enough in the past.

Anyways, thanks in advance and lemme know what you think.