My cousin had knee replacement surgery 2 weeks ago.  Tonight she discovered a lump behind her knee and she is worried it might be a blood clot.  She does take warfarin and wears the stockings that are used to protect her from clots.  There is no discoloration or warmth to the lump but she says it hurts like cramping.
Hi, It could very well be a blood clot. I suggest you see the Surgeon who has operated and let him examine your Cousin to see what is going on. Most likely all will be well and there usually can be blood clots after surgery which resolve spontaneously over a period of time and there should be nothing to worry about. But it would definitely be better to get it checked up. All the best, Take care, Chat Doctor. 