pain in upper left leg/hip

I am pathetically overweight at about 300lbs....diets are not working....but...I still believe I will win and lost 100lbs in the next year.

However, two days ago my hip/upper left leg began to very very sore on certain steps in my walk.....one step..fine...second step holy c**p what was that??? Knife in my hip feeling OUCH!!!!!!!

nOW...2 days later....the pain is incredible...>I cannot walk......I can limp and every now and then the pain hits me so hard I sometimes yell out..... I am using crutches around the house today that dont help much because I still have to put SOME weight on it....

Whats your best guess people/doc?

Thanks,
Tim