well, doctors get paid to be wrong
good luck with everything... i don't know what to do
here is something you should try though:
this procedure is for long term back pain elimination but it is also one of the most important means of immediate relief. First I will describe the pose, and then I will tell you how to become limber enough to achieve the pose.
Legs Up the Wall
Clear a spot in front of a blank wall. Lay on the floor with your legs straight up resting on the wall, hands at your sides. (How you slide into this position is up to you, there are a few ways.) Relax and pay attention to your breathing, making sure to completely fill your lungs. Scan your body for muscles that you could relax more without losing correctness of form. Feet should point forward, knees fully extended, heels reaching upwards, spine and neck straightened by and elongated on the floor. Arms at sides with fingers or palms up wall by default, but also try straight up parallel to legs, or clasped behind head on floor (good neck stretch) If legs fall asleep, pull down to chest for 10 seconds and put back up. Do not fall asleep in this pose. Do not bother with this pose if you don't intend to go at least 15 minutes. Even wearing clean socks, this pose leaves marks on my wall over time. I find that tying or belting my feet together so that I do not need to consciously keep them straight makes my own stretch more correct. You might also try tying or belting your knees together or to the wall. You want to relax as many muscles as possible. You might benefit from folded or rolled towels under your lower back.
It is fine to fidgit a little and make adjustments from time to time; scooch up closer to the wall, arch your back briefly, that sort of thing. Hold the stretch until the sensation is too intensely bad to reasonably continue. At first it will feel like nothing, and you'll wonder why I've typed all of this out. After awhile, your muscles will start to realize what's going on, and you'll get that stretching type pain. Then, after probably 15 minutes or so for a new practictioner, your back will start to feel just plain wrong, like you are damaging it by laying there. Gently roll out and lay on the floor for a minute or two, and you're done.
If you cannot reach a straight up-and-down angle, then a less than straight angle will be fine. Bend your knees or sit back further from the wall. Use towels for padding or to reduce the intensity of the stretch. Be creative in steadily approaching your goal of approximately-correct form.
Practice this stretch up to 2 times per day. Before and after sleep, or before and after a strenuous activity. Eventually you will be able to do the stretch for much longer, and will need it much less often.
Everybody is built differently, and some back problems/injuries will not allow you to use this stretch, but otherwise if you can achieve near correct form and be able to hold it for a half an hour or more, you should be largely impervious to back pain, especially lower.
I don't have your back injury so I can't tell you whether or not this stretch is right for you, but it is a very gentle stretch so as long as the pressure on your back from the floor is not harmful, you should be alright. You can always use padding, too (folded sheets, rolled towels, pillows)
best wishes to you