The medications contained in Fioricet are, Acetaminophen, butalbital, and caffeine. Some time ago, when my headaches were much less severe, I took fioricet and it did provide a little "calming" effect so I could rest and sleep, the acetaminophen alone wouldn't provide that for me and we are all pretty familiar with caffeine.
I'm trying to see if I understand what you mean in your post...the medication is treating the SYMPTOMS of your headache (the pain, tension etc) but no, it is not getting to the "root cause" of your migraine/head pain. Basically, it is not travelling to the nerves, blood vessels etc and "fixing" anything to avoid future pain episodes.
As far as you having a VERY SEVERE headache as you mentioned, I don't think your taking fioricet now has anything to do with future episodes. Are you asking about
building a tolerance to the medication???
Just a little clarification and maybe I can help. I'm sorry...it is 2am and I should be asleep