Glad to hear you are healing up well in general. The pain you experienced with the drain removal was just the irritation of the nerves around it. Now that it is out, you should be OK. Using drains in Breast Reduction may be helpful in avoiding fluid collections on the inside, and many plastic surgeons use them, but taking them out is a pain-- for real!
There are two explanations for the pain you experienced from the drain removal after your breast reduction surgery. One, the drain had a hub on it. This is an enlarged area that goes around the drain and is located just below the skin. It will stretch the skin causing pain when it is pulled out. Two, the drain was a standard JP (Jackson-Pratt) drain with holes on the side rather than grooves running along the length of the drain (Blake or Channel drain). If the "holed" drain was used tissue grows into the holes during the seven or so days the drain is in place. When the drain is pulled it really hurts. If the drain had the longitudinal grooves then when the drain is pulled these grooves glide across the tissue and there is little or no pain. The key...use a hub-less grooved drain to avoid the pain.
Drains can be painful when they are removed. I personally see no need to use drains and never done so with breast reductions.
Drains are sometimes an necessary evil. Some pain on remove is expected. Sorry it hurt you so much but at least it did its job and was removed.
Sometimes the drain causes pain upon removal. Fluted drains can hurt more, also drains that may be stuck to sutures can be more painful. Hard to say without treating you.
Thank you for your question. It sounds like your drain either had a large hub which caused friction upon removal, was caught by a suture or slid against one of the nerves that gives sensation to the breast. The good news is that it probably did not cause any major problems. If the pain persists, discuss it further with your surgeon. Best wishes on your recovery.
Sometimes drains have a hub that sits just inside the skin and prevents them from sliding out. When pulling them, the hub stretches the small opening for the drain and causes pain. Othertimes if the person removing the drain is not aware, a suture holding the drain in place is not cut and the drain is pulled causing the suture to pull your skin. Sorry about your experience. Luckily it is unusual. Best wishes!