Wah no worries lah, pasty poop after formula change very normal one! My friend's baby also switched formula last year and she was panicking until her PD told her pasty like peanut butter texture is actually what healthy formula-fed baby poop supposed to look like. Someone in my mum WhatsApp group also mentioned Karihome being goat milk base can make poop a bit thicker and different colour compared to regular formula, so that explains the change. But since your son just recovered from two weeks diarrhoea, still worth double-checking with your PD just to be safe yah!