sounds like the first stages of depression to me.

A couple of years ago I went through the same thing, I had to smoke a lot more than my friends to get high, and even after long tolerance breaks I would not get very high. I even made posts just like yours and got very similar answers.

sadly they were all wrong and my depression got worse and worse until I nearly killed myself. go to a counselor or a doc and talk about it, dont be worried about being labeled or judged, your life is more important than your ego