FIRST OFF, you ARE doing GREAT!!! with him! Don't sell yourself short on that! You are OBVIOUSLY a GREAT mom if you have a "very patient 7 year old" too!
Now, part of today's explosion could be BECAUSE he's sick. If he doesn't want the diaper, it may be because his bottom hurts from the diarrhea. Let him run naked for a few minutes. (I know it’s scary at that age. My son is officially 2 ½ today, 6/29.) He may be asking for some time to “air out” down there.
As for the throwing- I don’t know if it’s a “2 year old thing” but I KNOW it’s a “Boy Thing”. My son throws things ALL the time. Depending on what it is and why, I do one of the following: if it’s a ball I remind him “we roll the ball inside, or take it outside to throw.” If it’s a toy that shouldn’t be thrown I tell him “Either you go pick it up right now and put it where it belongs, or Mommy is going to pick it up and put it on time out way up high.” Then I follow through with just that. I ALWAYS put it in a place where he can see it from where he made the “violation” but he can’t reach it on his own. When he cries and tells me he wants it back, I say “I’m sorry be you choose to not play nice with it, now it has to rest until you say sorry to Mommy and stop crying.” He can then choose his next action accordingly. (I know it’s hard to listen to them SCREAM because they aren’t getting there way, but if you give in, you’re giving UP!) If it’s something he KNOWS he isn’t supposed to play with, I make him pick it up and put it back. EVEN if he’s kicking and screaming and I have to FORCE his hand together while he fights me every second of it, I still MAKE him do it. At the conclusion of ANY of these situations, I ALWAYS thank him for making better choices. EVEN when it’s me FORCING him to do the right thing! If it’s something I’ve never told him he couldn’t touch, I walk over to get it myself and calmly tell him “Thank you for showing Mommy that she left this out where you could get it! Mommy is going to put it right here, but you’re not allowed to play with this one.” The same thing seem to work okay for him hitting others too, whether on purpose or on accident. On purpose I tell him he has to sit on time-out until he can say "Sorry", on accident I tell him to say sorry and he usually does.
As for you starting to cry- again, TOTALLY within the normal range. People deal with stress in different ways. Him seeing you cry probably shocked him. If you find yourself crying about EVERYTHING, then talk to your Dr. It could be a sign of mild depression. (Depression can be a side effect of stress and vise-versa.) I cry like a baby at least once a month- I’m sure you can figure out when! :O)
Just remember, you are a GREAT mom! Keep up the good work you’re doing with both of your kiddos! This too will pass! ~J.