I started having back issues 30 years ago. I ran hard and fast, and rode bikes, and especially, backpacked and did mountaineering for fun. One day I bent over at the waist and picked up a kid. POw! I was in excruciating pain, and once in the house, could not get up off the floor or bed. It slowly got better, but never went awaycompletely. I was able to backpack, cycle, but not run. I could train for a big peak by walking on a treadmill, but running would not work for me.
8 years ago, age 56, I was feeling strong and fit, and did a stupid event that pounded my back, and the next day did a second pack pounding event (mountain biking downhill on a washboard road). That night I could feel the numbness moving down my left leg, and it was very painful. I went in to the emergency room, barely able to walk. I got on about 5 different meds, and had an xray when the swelling went down. The photo clearly showed a bead about as big as a pea pushing out of my disk, and pushing on the sciatic nerve.
The doctor said no problem, a quick nick with the scalpel and that would be fixed. A soccer team parent was a nurse at an orthopedic doctors office, and she said try to walk it off, and delay surgery as long as possible.
I walked around the soccer field, and it would take me the whole hour the make it around once. Gradually, it got better. I was afraid of getting on my road bike, so I got a recumbent trike, and found it so much more comfortable to ride, and it was hugely fun. I've ridden it every day since then, and its the highlight of my day. I did a 35 mile bike event last weekend, and I did very well.
Luckily my backpack hits me just where some pressure feels good, and I can backpack fine. I do try to keep my load light, however. I do free weights, cycle every day, and have started doing yoga. I'm ok for a 40 pound pack, which is about what I have for a 7 day trip.
I would keep at it, and walk as soon as the pain lets you, and do exercise and yoga. Recumbent bikes are great for exercise and back support, and man are they fun!
more info about recumbents: bicyclepatents.com
more info about my backpacking: backpackingtechnology.com