hi dear.
see its not neccessary that stretching ur spine or any muscle related to it can heal it. one of the cause for ur disc injuries may b weakness in your lower back muscles. although i hvnt seen u physically but it can be recommended that you must go for some strenghthening exercises ie. back extesor training and abdominal exercises but start with mild ones first. and regarding the cold sensation in ur lower limb, it may be due to the compression which ur hrniated disc is giving to the spinal parts. nand one thing more, go for some spinal braces as ur spine needs some protection and support.
gud luck