Sounds to me like you need abit of rehab mate :P

To do this, forget heavy heavy weight atm and take out some light weights. Focus purely on stabilising the muscles of the erector spinae on both sides and lots of different types of bodyweight exercises. Do this for 4-6 weeks.

After the 4th-6th weeks depending on how severe it is, progress onto light weights to build up that much needed endurance and mix this with medium weights to gain that half way point strength / endurance. Do this for 4-8 weeks.

After that you should have built back up a stable back which is strong and flexible. Do NOT forget flexible . But for a more detailed programme, pm me