bitterspeak

I am currently riding a Fuji Roubaix Pro with FR 105 and RD Ultergra. When I first got the bike (which was in April or May), the shifting was extremely smooth. But recently the shifting from the RD has become rather poor. Whenever I I downshift or upshift the rear derailleur, it feels very clunky when it changes gears. The chain feels like it's being dropped from one gear to the next and it feels like there is a slack. So after I shift, instead of having instant power, I pedal an inch of slack before the power is actually there (Let me know if I need to clarify on this).

I brought it to my LBS, and they said it was loose cable tension in the RD. So they did a quick fix and the downshifting felt better but my upshifting still felt a tad clunky. This past weekend, my cousin came to look at it and tried to spend some time with the bike. He tried tuning it with the adjustment barrel and tightening the cable tension even more but it seems to have gotten worse. He said I should try cleaning my chain or even replacing the shifting cables.

If this is important, the bike also fell derailleur side once. And I was wondering if this would matter at all? It wasn't a hard fall but it did scratch up the rear derailleur.

So I was wondering if you guys have any suggestions as to a possible solution. Advice would be much appreciated.