My first thought was that maybe Tomikawa recognized what she was doing and bumrushed to get the donuts as a result. Last chapter she recognized that Hiiragi hadn't actually done anything wrong, and she knows that she's being put through academic abuse.
That tells me Tomikawa has a certain degree of self-awareness, even if it's clouded by her emotional instability. So I theorize she realized what she was doing, maybe freaked the fuck out about being like her mom/driving away Hiiragi/etc, and in her mania blitzed to get the donuts in a misaimed attempt at reconciliation.
So, y'know. Two steps forward, one step back.