Causes of Lower Back Pain Video. Lower back pain from muscle strain usually is caused by any type of movement that puts undue stress on the lower back. Frequent causes include lifting a heavy object, lifting while twisting, or a sudden movement or fall.Sports injuries are also a frequent cause of a pulled back muscle, especially with sports that involve twisting (such as golf), or any types of sudden impact or jarring motions.In This Article: A muscle strain happens when the muscle is over-stretched or torn, resulting in damage to the muscle fibers (also called a pulled muscle). 2  A lumbar sprain happens when ligaments are stretched too far or torn. 3  Ligaments are very tough, fibrous connecting tissues that connect bones together.
A rotten egg smell is usually caused by an animal in the ventilation system. Sometimes a small rodent or bird will crawl into the vent while sick, or become trapped inside. Once the animal dies, the decomposing carcass gives off the smell. Once you turn on your HVAC system, the smell fills the entire house. Ventilation and duct cleaning is the best method to solve this smell.
As far as the smell coming from the a/c system, if it is a mildew smell, then it is from mildew building up in the a/c evaporator case. That will occur if moisture stays in the evaporator case too long before draining out through the drain tube that comes out under the right side of the vehicle.