I feel light headed after a smoke while in recovery

5 or so months ago I had a longboarding accident where I got a pretty bad concussion and a bit of bleeding in the brain (blood clot). I am supposed to take 6 months off of smoking, drinking, drugs as well as any activity where I may hit my head such as skiing, longboarding and even roller coasters. I have recently started smoking again. And when I smoke I get lightheaded and sort of high. The really weak high. Is this normal? I have smoked before, but not as much as I do now. I also smoke the real way where it goes into my lungs for sometime, not the pansy way. Is it normal? Please spare me of the "smoking is bad for you talk." I already know I just want to know if it has anything to do with my injury.