Hey, Aura, welcome to CC.
Not exactly the same issue but I get knee problems if I don't ride frequently. Is there a chance, however slim, that finding a bike which is just the right shape for you will allow regular, gentle movements which would do you some good?
I'm afraid I don't know much about curvature of the spine, but I'd definitely be looking for advice from a medical professional who knew about your particular issues.
I'm fairly certain that you'll be able to find a bike which didn't give you pain. Somewhere between the hunched-up sports bike with dropped bars and the sit-up-and-beg Dutch style there will be a flat-barred, relaxed road bike which is just begging to take you for a ride.
So, go and speak with your doctor, then, if they give a positive response, go and speak with your Local Bike Shop.