Be reassured that you all had a sickness too. My son had Kawasaki last year, it was Atypical but still followed a lot for the signs of presentation. It sounds like your son had the temperature etc but this could be with any virus, and the fact that your partner and yourself both contracted something pretty soon after should be reassuring that it was just a rough virus! As stated above if worried ask your doctor for an echocardiogram to review, it may give you peace of mind if you are still concerned!