Marisha's entire hole-ridden body is flat-flat and hurt-hurt, but being in the palm of Mwommie makes her feel "happiness~" that exceeds the pain. She takes it easy and rub-rubs with Mwommie's hand.
ぺらぺら can mean both flat/thin or flimsy/weak so it could also mean 'Marisha's body is weak and in pain'yuyu"Mwommie... do wick-wick..."
Maricha reached out to Mwommie with her small braid.Mwommie lifted Marisha's body with her left hand and looked at her whole body.
It does spell Marisha instead of Maricha in jp, artist did a typo