Hi there,
well, I am not a doctor but I did manage health clubs for the largest chain in the country for many years. First I would ask, what kind of weight lifting are you doing? What are your workouts like?
Generally, I would have not recommended any weight lifting without a doctors consent. Since you got that, I am wondering what the severity of your problem is? How many visits have you had with this physician and for how long and what type of doctor is he or she?
If you are still having that much pain, I would not do any weight bearing exercise that involves that area of the back. I would get another opinion, the shots that you are getting will do nothing to get rid of the problem, the shots only mask the pain associated with it.
Additionally, I would ask other than school what other activities are you involved in? If you are even gaming or on the computer for long periods of time, this can put pressure on that area as well, never mind any sports you may be participating in!
In short, if your pain is still that bad, get another opinion. That person should make a plan to put you back on the road to wellness.