Bubs is having an allergic reaction is it safe to put him to bed?

My son had red bumps on his chest and red cheeks. My husband was with him so I didn’t see it until it was bedtime. I gave him Benadryl and Tylenol, is it safe to put him to bed? He was super tired and ready to go to sleep. I’m nervous because I’m not sure what caused it (could have been from a new shirt or him eating from my plate). It looked pretty mild but still worried. He’s 16 months old.