I have been having serious backaches for the past 3 days.

Doctor can evaluate: Some possible causes of lower back pain include: back muscle strain, back ligament sprain, herniated disc, spinal stenosis, osteoarthritis, urine infection, kidney infection, kidney stone, tumor in the spine, tumor in the kidney or other places, fractured vertebra, fibromyalgia, certain bacterial infections, etc... With such a long list of possibilities, one's doctor can evaluate the details.