Lower back pain?

[JDiggy]

It could be just muscle soreness, it isn't an agonizing pain but just annoying. I've been working on my deadlift form for a year or so now and I still don't think I have it down 100%. Whenever I do heavy deads 5 reps or less I get a pain or just muscle soreness in my lower back lasts for about 5-10 minutes after doing the last set. It isn't on the spine its off to the sides of it just above the butt. This has been happening for about 3 months now at first I just thought it was muscle soreness but within the last week I've found sleeping on my back like I have for the last 18 years to be uncomfortable and I get a bit of pain in the same place I would after doing heavy deads. Would like peoples opinions on this and if I should go see the doctor immediately. Also I don't do core work very often and read in another lower back pain thread that with a stronger core and keeping it tight throughout the entire movement might help alot?

[gimpy835]

stop doing deads, stretch, do core work, try heat and ice to help with pain, ibuprofen if you notice any swelling.