Today I had 4 players from each team underneath and I knew they fouled but they had so many going on I didnt know who to call it on and what foul to call. What to do in this situation?

Simple. Call the first foul you see on the correct player. Ignore the rest of the contact unless intentional or flagrant because you have a dead ball situation.

If you can't do that, get more training.

This may sound cold and harsh, and I don't mean it to, but that's what you're going to have to learn to do. You can't ignore fouls just because there are a lot of players and they're fouling a lot at about the same time, and use that as an excuse. Kids will get hurt that way.

Call what you see
 

Do you really know that they were fouls or do you think there had to be because there was some much going on? Yesterday in a game was doing the coach kept yelling " you gotta call something" every time we had multiple put backs under the basket. During a dead ball I told him I was not going to make something up just beacause we have a flurry under the basket, and I don't "HAVE to call something if there is nothing".

Speaking of fouls underneath the goal. I had a varsity boys game a few nights ago. I called a PC foul on a player when the defender was under the basket. The coach for the player that committed the foul about went nuts. He told me that you couldn't call a player control when the defender was underneath the basket. I didn't have a Davism for him so I reported the foul and moved on.

You could tell him that you'll be reffing NBA games before he's coaching them, so he should leave the rules differences up to you!