Tiredness and headaches?

Recently, especially this week i've been waking up feelinng extremely tired and having constant headaches, leading me to not even wannaa smoke my usual 10 a day fags, instead its more like 2 or 3 (which I suppose thats a plus), I know I jhave been stressed and down latley but I have always had this without the tiredness and headaches, when I look up tiredness without reason online alot of things am linked to early pregnancy but this does faze me as the last 6 months I have unprotected sex with my bf but have not fallen pregnant, my period finished Friday and only again had sex this week once in 3weeks sso I am ruling out pregnancy. Is there anything else that be causing me 2 feel this way?