1 year old only wanting bottles, refusing food, waking up several times a night

So my second born turned 1 a couple weeks ago.

For the last couple weeks he has not had any interest in ANY food at ALL. He only wants his bottles. He was a great eater and up until a couple weeks ago, now he only wants his formula. And it’s not just a couple bottles a day, I mean he’s sucking down 8-9oz every couple hours. When he’s hungry I always offer food first but he will shake his head, push it away, scream and cry until he gets a bottle. I’ve done this a million times until I give in because I don’t want him to be hungry. Is this something I just need to be tougher about and only offer food ? Is this just a phase? The other issue is he is waking up 3-4 times a night for a bottle. I mean 6-8oz bottles 3-4 times a night. It’s kind of insane and I’m losing my mind feeling like I have a newborn again. Because he’s pretty much only having bottles, his poop is now super runny and yellow again like a newborn. Could this be a phase? Teething? What is happening ?!?!

Never went through this with my first so I’m just trying to see how to deal or if this is even normal.

Super sleep deprived and stressed. Have an app, with his pediatrician next week to see what he suggests.