Symptoms shouldn't be ignored so easily

Check with your doctor. It could be anything beyond what this list says. Some are acute, but some aren't. Here's a back pain possibility:

#16 The Warning: Severe back pain
What it could be: Aneurysm

Similar to the kind of agony you’d expect if you’d just tried to clean-and-jerk a wardrobe. The usual remedies - heat, rest, OTC painkillers - offer no relief. If it’s not related to exercise, sudden severe back pain can be the sign of an aneurysm. The pain subsides after your body’s main artery bursts. A less threatening possibility: You have a kidney stone.
A CT scan reveals the size and shape of an aneurysm. Your doctor will prescribe blood-pressure medication or surgery to implant a synthetic graft.