I had a breast augmentation 8 days ago. Yesterday I fell down a small flight of stairs. Should I be worried? (photos)

This photographs is not very helpful to tell whether anything is wrong.  You must check in with your surgeon to be sure.  A rapid swelling could be a hematoma, which may require surgery and could result in a capsule later.

It is not possible to accurately access you from the photos provided. Hematomas, or a blood collection will make the breast very tense and usually have a great amount of bruising. If there is fluid in the  pocket ,it will usually resolve without problems. Follow up with your surgeon, they can best advise you.Yours,Jon M. Grazer, MD, MPH, FACS

Thank you for your question, you should follow up with your chosen plastic surgeon to discuss your concern. Best of luck.

It is unlikely that you will experience complications from your fall.  A hematoma should not develop later as a result.  A fall in itself, without other problems should not cause a contracture.  If bleeding after your fall did occur, this could be a risk for contracture.  The swelling could be due to a number of factors and may or may not represent bleeding.  I would see your surgeon immediately to see if anything needs to be done.  

A sudden increase in size of one breast after surgery especially after some trauma like a fall could mean that there is some bleeding around the implant.  Because of this I would contact your plastic surgeon and make it a point to be seen because treatment may be necessary.Bleeding around the implant or a hematoma can increase the chance of capsular contracture.Best of luck.