The only way you'd know if his PA or CA changed, was if you looked using FM Genie Scout or FMRTE. If you used FMRTE, there's a fair chance that you accidentally edited the PA, if as you say the PA changed, or if using either of these programmes, it is possible for your save to get corrupted, which could also result in such strange occurrences.
Either way, as last poster said, PA does not change ever, but CA can change all the time, particularly after a long injury, as your player suffered.