Pain at site of drain

I want to make sure I'm coding this correctly. Patient with gallbladder drain following postponed gallbladder surgery. Now presents to outpatient clinic with pain at the drainage site.

Exam shows drainage working but with presence of some blood in the drainage fluid. No inflammation. Pain on palpation of site.

Provider's Assessment:
Calculus of gallbladder, 574.00.
Constipation, 564.00.
Abdominal pain, 789.00.

Plan: Pt to contact surgeon for drainage site revision. Now given RX for naproxen for pain and docusate for constipation.

Am I correct to code as:
Post-op pain (338.18), abdominal pain (789.00), constipation (564.00)?

I do not think I need to put the calculus since this provider did not treat that specifically (?). Do you agree?

Also, do I need to code the presence of the drain? Is this considered aftercare? But nothing was done (no change or removal of drain). If so, the closest I can find is V45.89, Other postprocedural state.

Thanks for putting up with my many questions! I am so grateful for the help I get here! :)

Pain at site of drain