Hi thanks for your question.
You had injured your knee two and half months ago, when you fell on a concrete floor.
The knees are now swollen tender and you there is fluid inside.
Since you’re walking from last two and half months, so fracture
of knee cap or any other bone associated with knee joint is ruled out.
You have not developed fever
during this period, so, this injury
has not got infected.
But there is inflammation, of joint that has caused swelling, tenderness and accumulation of fluids inside joint.
Consultation with a physician is urgently needed to prevent further complications that are infection and septic arthritis
Hope this answers your question.