I Am Haveing A Lot Of Trouble With A Total

i am haveing a lot of trouble with a total knee replacement it was done on 1/1/15. I am in a lot of pain is this normal . It is were when I went home from rehab after 3 week able to bend it 120 degree with somewhat moderate to little pain an had a bad attack of were i had trouble even walking on my foot ankle the knee hurt so bad to try to bend and the doctor would not give me any pain meds and still wont and still having a lot of pain an i can only get 100 - 110 degrees with a lot of pain with me being in tears all the while the therapist is bending it ti get it to go to the 110 could you possibly tell me what might be going on