Stomach problems are in my opinion a reasonable explanation. Regarding climbing performance in the past few days. I wouldn't pin point that to lack of experience, minus nutrition, or mismanaging the peak. As stomach problems should be resolved now, likely we will see better climbing performance tomorrow. Timing basically being perfect.
Good luck tomorrow Primož. With good legs and a bit of luck pink jersey is still in reach. As for the best possible strategy. I guess Primož an his team now need to decide if full attack (possibly Manghen), saving some strength for TT or something in between makes the most sense. This will likely be impossible to plan ahead. The tactic will need to get adjusted during the tomorrows stage. Nibali will likely go for it (Manghen) and hopefully Roglič will be able to respond and Carapaz might struggle.
Good luck tomorrow Primož. With good legs and a bit of luck pink jersey is still in reach. As for the best possible strategy. I guess Primož an his team now need to decide if full attack (possibly Manghen), saving some strength for TT or something in between makes the most sense. This will likely be impossible to plan ahead. The tactic will need to get adjusted during the tomorrows stage. Nibali will likely go for it (Manghen) and hopefully Roglič will be able to respond and Carapaz might struggle.