that could be anything from a shock to a bad ball joint, to a failing wheel bearing, or loose lug nuts,, could be a lot of things,, your ball joints are on the upper and lower control arms if you jack it up and grab the wheel move it back and forth you'll know if there bad because you will see them move and feel it.. there are greease cirts on these they are supposed to be greased periodicly,, if its them it might be to late to grease them.. might just be a faulty shock.. you might want to get them checked,,, if they go completley you will loose control of your vehichle,(hense the term control arms) they control your front tires,, also check your tie rods, they also have joints that need to be greased,, also check the botls that secure the control arms to the frame. take it to the shop.. you said its doing it more now that means somthing is failing..
sevety9