We are having a discussion about carbon monoxide poisoning and treatment.
I had a case from a diver on a boat I ran of mild CO poisoning from a boat engine after a dive, he was a professional and the dive profile and safety aspect was very good.
After telling me the symptoms I thought decompression sickness but the O2 treatment seemed to make the condition a little worse, which is not usual of deco sickness. After calls to a doctor and attaining info of the boat fumes she said keep him off the O2 for a small time as this may be not helping the situation, without oxygen he felt a lot better and went back on O2 a while later making a full recovery.

Why would the initial treatment not have worked/ poss made the situation worse? As in most studies O2 treatment is always recommended.