When I run water in my kitchen sink there is a terrible foul odor throughout my trailer,it is making us sick is there anything that I can do or use to get rid of this??

You meantion a leak in the title... then go on to say only when you run water.

Is there a leak only when you run the water and the odor occurs at other times?

If that is the case... there would be a drain leak on the sewer side of the P-trap. I can't see a reason it would occur ONLY when you run the water unless the water itself has a foul odor.

If you have garbage disposer, it can produce smell coming from decaying food left over inside. Also, look under sink to see if you have P-Trap installed ( the J-like bend pipe ). Wet kitchen cabinet can smell but not only when you run water. It would smell all the time.