What are you doing between lifting sessions? Lots of movement and water drinking helps to flush the lactic acid from your muscles. I make sure that I'm more active on non weight days (run in the morning and at least an hour long walk after supper). A week is a long time with DOMS. Are your jumps in weight levels maybe too much for you? I'd be seriously concerned with needing that much recovery time. Are you supplementing at all? Is your nutrition up to snuff (otherwise recover is harder). Oh, and stretching! Are you stretching?
When I have pain for more than 2-3 days, I ensure that my next session I do not up weights at all. I look at it from the perspective that I've injured myself. So, I go slower during my sets, and I may even knock it down one plate or level and go to failure on my 3rd set.
This is just what I do, and how I handle it. I'm curious to see what the gym rats and experts here have to say!
Rough start due to major carb WD.
MWF: 1 hour run/walk, 1.5 hours in the gym - upper/lower and core
Sat/Sun=Yard/house work, chasing kids, playing
Family walk every night instead of everyone vegging in front of the TV
Personal trainer to build muscle mass & to help meet goals