Hip and groin

After moving a fridge freezer and a washer with the help of my  knee i developed a mild pain in both the hip and groin a couple of days later which got to the stage where walking was so painfull i went to the local hospital.I was told that i had damadged the muscles from my right hip to the knee and was put on anti - inflamatories and told to see a physio.Four months later i was still getting pain in the hip and groin and then was unable to put any weight on my foot one morning as the pain felt like it was coming from just above the knee and around the sides of the knee.Iwent back to the hospital due to the pain and the swelling of my knee where i was told i had pulled my hamstring.After resting it for over a week and taking painkillers i started to walk alright on it again untill i got out of bed the day after to be in severe pain again but this was now around the thigh area.The one thing i can't understand is why i can walk on it for 20 miniutes or so and then after resting it im back to square one again in pain trying to get it going again so please can anybody give me the reasons why.