steering issue

i have a small problem that may lead into a big one. i'm driving down this one stretch of road at between 45-55 mph. it then starts to do a jerky swerving. my steering wheel is not moving but the jeep is swaying back and forth. i can counter the swerving but i am worryed about what it is. what do you recommend to do?

i was thinking about getting my steering fluid flushed. but what else should i check for?

by the way it seems to only happen on this one road BUT its not the road. i have taken a few other cars down the same stretch and have no issues.

ask any questions you want to but i won't be able to repond tonight. its to late and Family Guy is on.