I'm really worried about my dad. For the past few days, he's been complaining of severe back pain and just seems super tired. He's also been having trouble breathing normally, like he has to take deep breaths and it's kinda like he's struggling. Plus, he feels like he might vomit but hasn't actually thrown up. Everything else seems okay, like his bathroom habits and appetite, but you can just tell by looking at him that he's exhausted. What could be going on with him?