Laxaly, there is no easy answer to your questions, I am afraid.
Although you give your age, you dont give your gender, which could have an influence on the symptoms you have... as an example, hot flushes and lightheadedness can be associated with the menstrual cycle in females.
The severe back pain and loss of sensation in your limbs needs a proper consultation. Add to that your other symptoms, and i would strongly urge you to go see your GP as soon as convenient.