Adderall

I take Adderall ir 15mg teva. I been on them since october 29, after being off of them for 4 years. The first month everything was great they worked really well. Today i picked up another script of the same medication it was totally ineffective, got a headache didnt get the usual kick focus or motivation and had a tight stomach from taking it. Is it a tolerance issue or is it in my head? Teva has no offical recall as of december 25 so i dont know whats going on im kind of upset confused and worried. Anyone else experiencing same issue ?