It may very well be a case of "he's developing well beyond what's expected". Is he a bright child? Does he learn new things quickly? How many tries did it take him to figure out crayons for example? Does he scribble with them, or is he actually using them to draw lines or something on paper, is he controlling them?
If he is very advanced, his emotions may not be keeping up. Yeah.. I get it that he's 2. But, if many things seem to come to him easily, he may have a VERY short fuse when things do not come so easily. Most kids give up after a few tries. Some try longer than others. Some give up and move on. Some don't give up at all but are so overcome with frustration that they melt down.
It totally sounds like he is frustrated. Being frustrated an explaining being frustrated are two totally different animals. And one usually interferes with the other. Not to mention, he is 2. He has a limited ability to explain whatever is frustrating him to begin with, even if he wasn't frustrated.
If it were me, I'd be in tears, too. But, if it were me, I think instead of asking him a lot of questions that he may not have the capacity to deal with... I would supply answers for him. Instead of "What's wrong?" or "Does something hurt?" or "Are you hungry, scared, etc etc etc?" I would look for the obvious and state it FOR him. "Oh honey, the crayon fell on the floor. That makes it hard to color doesn't it?" Then while handing it back, "Look, it still works just fine... now, what were we drawing... "
With breakfast, " I am sure you want to eat, and we will, right after the waffle pops out of the toaster. How high can we count before it pops? Let's see... 1,... 2....3..... " or
"I know you are ready to play with your _____, but you have to eat a good healthy breakfast for your body to be able to play hard. Let's eat first, then we'll have lots of time to ____. What toy do you want to get out first? "
Now, I realize that the above suggestions are kinda "fantasy land". You have 4 kids. You are not likely sitting there just you and him oblivious to anything else going on, or any of the needs of your other children. But I gave those "examples" so you could see the difference in the WAY the wording works. Instead of leading him to struggle more (trying to express something he may be unable to, or may not even know is his problem), you provide the answers/solutions. You're Mom. You're the HEROINE. You magically know how much he struggles with ____. And you reassure him that it will be handled and all will be right with the world. :)
Or not. He could just be a high needs child. :/ I wouldn't hesitate to ask my doctor about it, so long as you are able to do so without him or your other children hearing the conversation. I take issue with certain types of conversations being done in front of kids.
ETA: and well... he ISN'T two. (clicked back to a previous post). He is barely 20 months! Mom, he can't tell you the answers to the questions you are asking him. I mean, if he can... he can't do it while he's frustrated. And if it's something abstract, like "I'm tired"... umm... no... he can't express that.