4x04 Take Us Back plothole

so, in the barn scene, at the very end of the episode, Clementine was weak, had pale skin, had a hoarse voice, and had the little shaded bags under her eyes. Those are the characteristics of someone who is in the latter stages of the infection, and if a person has those symptons, it's because the infection has already spread. When Lee cut off his arm, he wasn't looking as bad as Clem in the barn scene, and he didn't survive. His skin was less pale, his eye bags weren't as noticeble, etc. You can look at other examples of bitten people, even in the TV show, that I know isnt in the same universe as TWDG, but the virus works the same. Every person who is bit and is on later stages of infection, AKA the stage that you either have to get shot in the head or turn, have these symptoms. The eyes, the voice, the pale skin, the weakness etc. So, this could only mean that Clementine was in the later infection stages, so tell me, how in the fuck did cutting off her leg magically get rid of it? If she was too weak to move, then the infection was already spread. I mean, cutting off her leg wouldn't suddenly make her skin start going back to normal and her strength start recovering. And you could say it's just a visual, but no, the weakness is important. If this was realistic, to survive, Clementine would need to be in the early stages of infection, which would mean that she wasn't weak, and that the whole barn scene would be 100x quicker.