EBF spitting up

So my little guy is 13weeks old and is EBF. Recently he has become very fussy when I go to burp him and now spits up really bad. What's causing this?? He will completely soak his outfit and an entire burp rag he spits up so bad. He's still eating every 3hrs. I've never had this problem with him before. Anything I can do to help keep it down? He's also quit pooping every day. He's only pooping every 2 or 3 days. Help!