My advice isn't professional of course, and I'm no way a doctor or even close to being one yet, but I used to have a massive pain in my leg and lower back. This is just from what I've recently self-learned.
I went to a doctor and they never gave it a name. They just told me it was a nerve being pinched... they didn't care to explain it more than that. They just gave me asprin. Didn't help. This was when I was playing soccer in high school.
Few years later, and being getting more interested in health care and medical stuff, I was reading some medical books and basic Anatomy & Physiology textbooks on my own. I came across a part about the spinal nerves and figured I'd read some of it, since I still have minor pain in my legs and lower back at times. Then I went on to do a bit more research on it.
Are you having pain radiate into your leg and feet?
I don't believe it's a muscle strain or tear. Nerve pain is usually described as being really sharp, and he emphasized it being really sharp.
It sounds like you have a spinal disc herniation (which is the medical term for slipped-disc... since 'slipped-disc' isn't an accurate name at all, since the disc doesn't actually slip out of place). To get an small idea of what that is, make an 'O' with your thumb and pointer finger, like you're doing an "okay" sign. Now stick your other hands pointer finger there.
The 'O' is your spinal cord, and the other hand's pointer finger is the nerve.
Now if you squeezed your other hand's pointer finger in that O, that's what's happening to your spine. Your nerve is being sqeezed, or pinched. What happens is that the disc between the bone ruptures, causing the nucleus from the disc to be forced into the capsule where the nerves exist, causing pressure on the nerve.
You won't always have pain in your legs if you have a spinal disc herniation.
Do a Google search on the lumbar and sciatic nerve to get more of an idea.
The sciatic nerve is the largest nerve in your body that starts from the lower back to the leg and down to the foot.
No, do not train or do anything that will put pressure on your lower back. When I was in high school, I tried to keep up with my team by running, going to practice, and playing games until I was forced to sit out of it all. The pain just gets worse, and the pain just stays longer if you try to do physical activities with it.
Try doing workouts that won't strain your back, or will at least keep equal amounts of pressure on your back, like laying down or standing up instead of sitting down.
I hope you have a lot of time to recover, it takes months to heal. For me, I missed out on getting to start my entire soccer season. I only played when I insisted "I was okay".
Give yourself at least 1-3 months to recover.
