After swimming our 1yo checks have been red and rashy at night time when i'm applying lotion to his cheeks he's crying like it burns what is this from?

Several things: Could be irritation from something in the pool, from sunlight, or from the lotion you're using. Does the rash occur when he swims everywhere, or only in one pool? Is the redness on his cheeks bothering him? If his cheeks are a bit red but he is unbothered, then he cries only when you apply lotion, then try a different lotion.

Look at the lotion: The lotion may have alcohol in it..That can cause burning. Have the rash examined by your pediatrician.