Help history teacher is calling me lazy ?

I'm getting diagnosed for dyslexia or epilepsy and he always calls me lazy all the time he's kept me behind I'n class every history lesson since September and I told him the school senco is checking me out for any 'concentration' problems but he went no ur lazy that's all your lazy he likes my brother he's smart but what my teacher dosent no my bro has aspurgers (sorry if spelling wrong ) and i bet that has never crossed his mind that my brother has that I've got this history teacher Tomoz what do I do if he keeps mee behind he scares me