Is it normal for one boob to feel like it’s in your armpit 19 days post op? (Photo)

From the photo provided, your implants appear to be in the correct position. I do not appreciate any signs of infection. Often after breast implant placement, the chest muscle can be tight and sore and can spasm for weeks after surgery. Give your surgeon’s office a call if this muscle tightness persists and they can advise you on the best way to manage this muscle soreness. Otherwise you appear to be healing well, and I do not appreciate any obvious abnormalities at this point. As usual, make sure to follow up with your plastic surgeon regularly for an in person visit to ensure you are healing as expected.

Hello,
Thank you for your question!
It can be difficult to assess you without doing a physical examination. It may be best to see your Plastic Surgeon to be assessed. 

Dear kaylalambert01,
based on your photo, it looks like your implants are not displaced. You are still in early postoperative period so some muscle spasms and soreness can be expected but there should be no significant discomfort, pain or asymmetry. If you have any concerns, I suggest you to consult your plastic surgeon and get an examination.
Daniel Barrett, MD

Certified, American Board of Plastic Surgery
Member, American Society of Plastic Surgery
Member, American Society of Aesthetic Plastic Surgery