I wasn't here in the middle of the night @kmakm - I hope you managed to get some sleep. I'm sure it's nothing but you're doing the right thing to get it checked out. If it helps at all, I have a vague memory of crying in the recovery room from the agonising pain along my rib bone near where the drain was. While it settled down it has never gone away and there are times when it's quite sore. I do wonder if there has been some collateral damage to that area - nerves, muscle..?
Everything is worse in the middle of the night.
Take care