Hi and welcome to HCM
As couple of weeks after injury
, knot(haematoma-collection of blood) is still there and increasing in size and painful to touch, it seems to be got infected.
It happens when after a trauma some blood vessels are wounded and blood flows into a muscles. "And thigh has a lot of muscles and a lot of space for hematomas".
I suggest you to consult your doctor for examination of swelling and if needed for drainage
Meanwhile use soft cushion for sitting and lying. You can take antiinflammatory drug like ibuprofen
to reduce pain and inflammation.
I do hope that you have found something helpful and informative and I will be glad to answer any further query.