advice please
 

hey guys, i recently changed out the track arms to get rid of an annoying rattle. it worked! i was so happy. no noise, no rattle. so i decided to get my wheels aligned. they were able to align all wheels except the right rear. they told me that i needed to replace the strut assembly AND lower control arm. they said that max'ed out the adjustment and can't do any better. however, now my problem is that since i got the alignment...i have a new clunk sound in the right rear area. is this coincidental? i brought it back to them and again, they said that it's because i need to change the strut assembly and lower control arm. now, remember, it did not make any noise prior to the alignment adjustment. so are they right? i brought it to another indy for him to check it out. he wasn't sure where the noise comes from either. it doesn't clunk when i drive over a speed bump or when driving steadily. it only clunks when i hit a small pot hole or when i change gears or just with slight deceleration or acceleration, ie quick slight jerks. i took a rubber mallet and hit the control arm to try to reproduce the sound. could not find it. however, when i hit the strut spring/coil, it does sound different from the left rear. so could this be it? it doesn't make a clunk sound, but it does produce a different sound. so..i'm leaning on replacing the right rear strut assembly. so i looked into buying the parts. it seems like the coil/spring does not come with it when i buy it brand new. so, should i buy a used part that includes the coil/spring? if so, are the left and right interchangeable? or.. am i totally off and barking up the wrong tree? any suggestions of where this clunk is coming from?

update...

i think it sounds more like a loose metal rod that is just hitting around. is there anything in the right rear fender like this? if so, how do i access?