15 month old teething (back teeth) is STILL sleeping at 4:30pm...should I wake him up?

He’s been extra cranky and hardly eating lately because of it. I feel so so bad for him. He fell asleep around 1pm; and is still sleeping (4:30pm) He woke up for about 2 minutes and just when I went to go get him he was sleeping again...

His bed time is usually 7pm. I’m not sure if I should wake him up? Or just let him sleep because he’s in pain...if I do let him sleep do I put him down at the regular bed time or make it later?

I’m a first time mama so I don’t know 😂