These are all good suggestions.
I am curious to know what type of work do you do? Do you stop to stretch during the day. There might be some flexibility exercises you can do during the day to decrease the tension you are accumulating in your back when you feel it progressing.
Likely you have already done this, however, sometimes the old-fashioned stuff really works well. Have you ever just pampered yourself by having a hot bath every now and then?
This might prove to be helpful until you can utilize other approaches.