6 weeks post arm lift and there are small arm pit openings on/near incision. Now thick, yellow drainage. (Photos)

It is common to have some separation of the incision after an arm lift due to the tightness of the skin.  Keep an eye out for obvious signs of infection and report them to your plastic surgeon.  It is best that you be examined by your plastic surgeon to see what his/her recommendations are as far as wound care.  Good luck!

Thank you for sharing your concerns and photos. It seems you're encountering delayed wound healing after your brachioplasty. Here's a brief plan of action:
Use Betadine, Bacitracin, or Bactroban on the incision twice daily.
Keep the areas dry; avoid direct water exposure.
Do not press on the wound; allow fluids to drain naturally.
Please urgently consult with your plastic surgeon for a hands-on evaluation. Although such wounds often heal well, direct care from your surgeon is essential.
Thank you,
Dr. Katzen.

It sounds like after the arm lift there might be a collection of fluid inside the arm. You should visit your Doctor and try to remove this fluid that is trapped under your skin.

This is not uncommon to have a wound separation in this area, just keep it dry do  not apply any ointments and it will heal in time, continue to follow up with your PS.

It is quite possible you have some fluid collection pockets under the skin following arm lift.  The body needs a way to let the fluid escape naturally, so those small holes are probably allowing the fluid to drain.  They may also be in areas of greater tension when you move your arms.  In time your body should naturally heal up.  If you do see signs of infection however, let your surgeon know right away.  Best regards.Dr. C