Hi Scoobs,

Is the pain worse a any particular times of the day? eg in the morning as you get up
How old are you?
Did you have an xray or any other investigaions/treatment after you had your fall at work?
How long ago was your fall at work?

It is hard to provide any particular sources for the pain without a physical assessment, as pain in the groin an be as aresult of many areas.
Commonly this can be the due to degenerative changes in the hip joint, or alternatively it could be related to a bony/ligament injury in from the fall
As it is aggrivatedd when you try to take longer strides it may be related to soft tissue tension/imbalance in the groin

Either way I would recommend that you seek a further advice in person so that an accurate assessment could be made

Wish you all the best

Chris