I've caught my boy Raja dragging his bottom on our beautiful wood floors

the past 2 days. It's not constant, just 2-3 times each day. I keep his bottom trimmed up and checked for "dingleberries" (sry if this is offensive language to anyone

) but it's clean & bare. I wondering if this might be compressed anal sacs or whatever it's called? Are there any visual clues that it could be this condition? Nothing looks swollen but I don't know what to look at or for. I need to go to the vet anyway for more heartworm meds but I could move the appointment up if it sounds like I need to.