Constant crying help

My son has never been such a crier. It’s been so difficult to put him to nap or sleep. He will scream/cry if I try to.

He just keeps crying and I’m going nuts

I don’t get any help

Usually he’s good I don’t know what’s up with him it’s been happening for at least 4 days now

He usually goes to bed at 7:30 pm

Yesterday he was up til 11

My back hurts from all the rocking

Help 😓