Her mania is a response to the fact she's realised she essentially tried to kill her baby, garnering sympathy the whole time, and gotten away with it. Wearing him wrong, filming him coughing and headbobbing, taking him to a party. He was often blue/purple, apparently not even feeding "for days". Remember when he first came into the world he was a cluster feeder, and how much she HATED it. I honestly believe she restricted his feeding which is why he went so lethargic and started refusing. All the while she was posting about how sick he was and how it was impacting HER, letting all that sympathy from her teenage stans who have no idea about being a mother or the true seriousness and extent of her actions. And then finally decided to actually take him to hospital, probably because Kurt begged. She is 100% on a manic "high" because she did all this, got the reactions she wants, and once he's better (I genuinely PRAY to GOD he gets better) she will be able to take him home with no repercussions. Having her baby didn't fill that void she had, its all these actions and the sympathetic responses she received that filled her cup. She will do this again.