About a week ago, i got a large bruise on my upper inner thigh. i noticed yesterday there is a large lump (a little bigger than golf ball) underneath ?

Hematoma: You probably broke a blood vessel with the injury and there is a collection of blood that is slowly being broken down which is the "golf ball". You should apply heat and take a nonsteroidal such as ibuprofen or naproxen for a few days to help kick start the process. If the bruising goes away but the golf ball remains for more than a week or two, you should be seen and possibly x-rayed.