So I had deleted this app a while ago because I got some hateful comments and I don't really need…

So I had deleted this app a while ago because I got some hateful comments and I don't really need that in my life right now. But my 2.5 week old is not feeling good and I need some advice/help. He is formula fed so he usually has formed poop and goes once a day. Last night he started getting runny diarrhea and he isn't wanting to eat. He's only had 3.5 ounces in the last 5 or so hours when he usually wants to eat 4 ounces every 3-4 hours. He's also been super fussy obviously because he doesn't feel good, it's just really out of character for him. I feel so bad I don't know what to do for him, should I call his doctor?