I have a thought about the baby but it's not pleasant - just wondering if it's died in utero but is not necessarily chomping it's way through her, rather the decomposition of the foetus is causing her to develop an infection.
Rick's reaction was totally understandable. He was already crushed when he had the dreadlocks in his hand thinking he'd lost Michonne and Darryl, then the Negan ambush tipped him over the edge.
It was chilling how Negan strolled around giving his monologue, smiling like he was on the whole a normal person, then in the last minute turned the smile off and became fucking terrifying, barking a few instructions then bludgeoning someone to death. Amazing acting.