To some extent: yes, the questions may well be too open-ended. Not even exactly too open ended, just asking for information that he doesn't necessarily have. Better is to ask for more specific categories, and better still is to not worry about any of it: get him to a calm place, then let him tell you on his own what's wrong, if there's anything actionable, anyway. Most of the time, particularly with nighttime upsets, simply having Mommy or Daddy snuggle him will solve any problem he's having.
Some additional detail:
It's hard to answer "why" questions when upset
"Why are you crying," for example, asks him to figure out why he's upset - which often is not possible, because he's upset. How often do we wonder why a child gets so upset for something small? It's not necessarily because that something small really is big to him/her - it's because it just made him/her unable to handle something changing, or similar.
When he's upset, it's going to be hard for him to figure out exactly why; sometimes, closed-ended questions can help, if you have some idea. I usually at least start with the following after night-time wakeups, in some order:
- Did you hurt yourself?
- Did you have a bad dream?
- Did you feel lonely?
One of those three usually elicits a yes. Honestly, though, other than the first, you probably won't find anything useful a lot of the time.
Children often find a consistent answer and stick with it
Here's a nearly verbatim transcript of many night-time wake-ups with my three year old (a year ago):
Did you have a bad dream?
What scared you in the dream?
He didn't really know why it was scary... just that airplanes scared him. Apparently. Even though they're one of his favorite toys. What happened, though, was it became his default response any time he had a bad dream - which meant "airplane" became code for "what causes bad dreams". I suspect most of his bad dreams weren't about airplanes - just the first one we talked about was, and that led to all others becoming so.
Ultimately, it's not always possible to figure out what's wrong when a child's upset. Even at four, sometimes it's just not possible to get to that point. At three, it's very common in my experience. Unless the 'what's wrong' is very concrete - "my toe is smushed in the door, thanks daddy for not paying attention" - it's going to be hard to explain exactly what's wrong, particularly after a nighttime wake-up and particularly when hysterical.
Give him the vocabulary
The best way we've found to help our guys get to the point where they can tell us, sometimes, what's wrong is to make sure they have the vocabulary - and I don't mean the word-vocabulary, but the emotional vocabulary. This is done both by helping talk through problems after they've happened - shortly after, but enough after that he's not hysterical any more - and by modelling the behavior with our own upsets.
I mean, every husband has said something wrong to his wife once, right? In front of the kids? It's going to happen (and the reverse, of course). Seeing how Mommy reacts, and tells Daddy that he said something she didn't appreciate, is part of learning for kids. Also, same when Mommy gets sick - how does she talk about it? How does Daddy talk when he stubs his toe or steps on a block. All of that is modelling behavior for your child, and helps him figure out how to say what he needs to get your help.
When he does have a problem, even if you can't figure it out in time to fix it - talk to him about it, and make sure he knows how to describe it. If he's in pain, I like to poke around and see exactly where the pain is - that helps him be more precise.
And of course, talk about emotions constantly. I ask my children all the time if they're happy, and if they're happy with me specifically. When they're not, we talk about why. I've gotten things from "I don't like it when you make me follow rules" to "I like Mommy today", as if loving parents is a zero-sum game. Sometimes it's just life - but sometimes you can change things.