Even if they did have pain it was probably a stomach ache from its shitty diet. The ER part actually sounds somewhat plausible, beyond the parts where the nurses were openly "fatshaming". A fatty like that complaining of stomach pain would be assumed to be faking for pain meds or attention, which it admitted to wanting. Being dumped off on another ER from the first one is a sure sign that they knew fatty was faking and just didn't want to deal with them.