Baby is sleep trained: what to do on sick days

My 8 month old has been sleep trained for almost 2 weeks now. He has been doing great even with his nap.

He got his flu shot tonight and the last time he got it, he ran a fever overnight. I made sure his room temp was down (he gets hot so easy), lighter sleepers and his fan close to his crib the way he usually wants.

Question for those who sleep trained, on nights that they are sick and extra fussy, how do you do it? Do you stick to the routine?

I am so tempted to just hold him to make sure he is good and feels loved. But him being sleep trained has gave him good amount to sleep that he has never had since he is born.

As selfish as this might sound, I hate to go back to square one but I hate to let him cry (I do modified CIO) when I know how he acts after his shots..

Recommendations or Suggestions anyone?