Thanks for writing in.
I am sorry to hear that you had a fall and large swollen bump in front of your thigh. If you are unable to walk and if the swelling is very painful and significant which is showing no signs of reducing, you may have to visit ER. As you say a hard, swollen large bump, it can be a muscle hematoma
. Diagnosis can be made only after clinical examination.
Ice and elevation will give you temporary relief.
Hope this helps.