Keith was never good with feelings. (a issue spending 11 years in a lab). So when he walked in on you clearly not feeling well, he didn't know what to do.

He stayed the the door frame before slowly walking in, closing the door behind him. Sitting down on the bed beside you.

"Hey, hey, what's wrong..?"

He placed a hand between your shoulder blades to try and comfort you. He didn't know what to do when comforting someone, but he'll try for you.