I said it's not a strong case, but I don't know your psychological background and I am not a doctor but my guess would be that it's probably not schizophrenia.

If you're doctor said that he could have either been an ***/ignorant/old school or he may think what you're feeling is just a normal amount of pressure and reaction based on your age group and associated stressors.

Lack of concentration or focus could be many different things. It isn't "strange behavior" but it isn't entirely normal. If it's interfering with your life then it needs to be addressed.

I think you need to consult with your doctor about the things you are worried about. If you think your doctor isn't someone you'd like to see anymore then don't be afraid to try for a second opinion.