Thanks for asking your query here.
It appears that there may be injuries to soft tissue
around knee joint (tissues/muscles etc) or injury
to ligaments in the joint or fluid collection in your joint. It is difficult to point to exact cause without clinical examination and x-rays.
You have not mentioned about your age? Whether you suffer from any medical problems or take any regular medications?
I would advise:
1. To take regular painkillers like paracetamol
2. Take rest
3. You can try lukewarm water massage
to the affected knee joint
4. Please see an Orthopedic Doctor at the earliest feasible day and time.
Wishing you speedy recovery
Dr Tejas Shah