I really feel for you....I have been in your position so many times and it's hard to have those weeks and then relapse. You really haven't lost them though. Every time you quit you are building more and more of the skills you need to stay quit. Feel bad for a day or two then get up and carry on. You CAN do it....it just takes some time.
Maybe see your doctor too about the blood. Do what you can to look after yourself. Sending some love your way
xxx