Hard and swollen breast suddenly while breastfeeding-capsular contraction or other?

Capsular contracture does not develop overnight.  You could have a mastitis (infection) as your physician has diagnosed, or perhaps that breast is more engorged with breast milk than the other.  In either case, I don't think you need to worry about capsular contracture right now.

Thank you for your question. Capsular contracture is not a process that pops up over night. Rather, it is a process that occurs over months or years. What you are describing is more along the lines of mastitis. You should be evaluated by your Ob/Gyn or primary care for management. It may take days or weeks to resolve.
Best of luck

If your entire breast is hard and swollen you may want to attempt massage to soften the breast. Visit your surgeon and have an assessment done. All the best.

implants over the muscle can very rarely develop lakes of milk or other seromas around them when nursing. It is not common but an ultrasound will help to clarify what you are experiencing.  You need to seek consultation from a board-certified plastic surgeon.

For questions regarding your surgery, always consult your surgeon first. He or she knows you better than anyone. If you are still uncomfortable then consult with a surgeon certified by The American Board of Plastic Surgery. You describe a situation that I refer to an ob-gyn physician for evaluation. Additionally I would recommend,  La :Leche League. They are a group of women dedicated to helping women breast feed and have an international experience for same. They were most helpful for my two children.Best of luck.Jon Sattler, MD

Your symptoms do suggest mastitis.  However I suggest that you see your plastic surgeon for an examination as well as continue to follow your obstetrician, as appropriate treatment of mastitis is crucial.Immediate onset of a capsular contraction would be highly unlikely.