'Teen Mom' Stars and Their Kids

"At the end of the day, he wasn't there, he missed the process," says Cheyenne.

"Teen Mom OG" is back and so is the drama between Cheyenne Floyd and Cory Wharton, the father of her little girl, Ryder.

In February, the then 22-month-old was rushed to the hospital with the flu, made worse by a congenital condition she has called VLCAD. The child was born with very-long-chain acyl-CoA dehydrogenase deficiency, which means she can't process fatty foods.

In a preview clip from Monday's season premiere, Cheyenne vents to her mother about Cory, who was out of town on vacation while Ryder was hospitalized. Cheyenne chronicled the baby's progress on social media at the time (below), something she says was helpful for her followers.

"Ryder being sick was one of my worst days," she says in the video. "But with me posting that, I probably received so many messages and emails of people that are dealing with the same thing saying thank you for showing what we go through."

"I always say, Instagram and social media is your highlight reel and you post your best pictures, you post your best things," she continues. "I've tried to open up and show my worst days."

Here's what she posted at the time:

View this post on Instagram

Emotionally and physically exhausted.. my baby has been pricked and poked going on day 3 at the hospital with an 103 fever & flu. It has been some of our longest nights together and all I can do is pray. Situations like these always make you snap back into reality and puts so many things into perspective. Ryder, once again you have taught mommy another lesson. Thank you 🙏🏽Thank you to my family that has stayed up throughout the night to pray with us. Thank you for my friends & family that came by, brought food, and offered support. Thank you to my mommy for always being my rock and staying at the hospital with us. At this point, I am asking for prayers. Praying today will be our last day here. Praying for Ryder to eat so we will be able to go home. God please continue to watch over us and guide us through this difficult time. I share Ryder’s medical journey to bring awareness to VLCAD and to the families that are constantly fighting. We got this. #RageRegardlessRy #vlcad

A post shared by CHEYENNE (@cheynotshy) on

"Corey missed all of it," Cheyenne then says in the video.

Adding that he did show up "on the last day," she gets frustrated as she says he's "never gonna understand" Ryder's diagnosis if he isn't around "the times where she is screaming like she's about to die."

"He's never going to understand what she has until then and he missed it again," she says. "At the end of the day, he wasn't there. He missed the process. So in my head, he still doesn't understand that your child has a rare disease and that when she has the flu or she has a fever, it's not a normal flu or fever."

"She could go into shock, she could have a seizure, she could die," adds Cheyenne. "You have to understand these things."

Explaining himself at the time, Cory tweeted, "Ryder got sick while I was on vacation and once it got worst, I booked a flight home. At this point I can't care about everyone else thinks I know what type of dad I am. I just want Ryder to get better."

"Teen Mom OG" airs Mondays on MTV.