Act now. Take him to a doctor. The sooner he is diagnosed (if he has it) and treated, the better his prognosis.
It might be just anxiety, it might be something more serious. A psychiatrist will observe him and interview him. The psychiatrist will tell you what it ISN’T. There are other certain conditions that mimic the symptoms of schizophrenia. So the doctor will test to make sure it’s not these other conditions. The first two of those things you list are paranoia. Lots of people have trouble sleeping occasionally for various reasons. Lots of people are overwhelmed with crowds. It’s actually very common and doesn’t mean it’s schizophrenia. Anyway, you can either take him to a doctor and see what the problem is or not take him to a doctor and live with the problems. Good luck.
I have an older sister who was diagnosed with schizophrenia 40 years ago. She currently lives at a nursing home. I was her best friend growing up and she still is. She is a huge part of my life. Therefore, I know her and I think I have somewhat knowledge of this illness. If you ever had schizophrenia, it’s most likely that you still have the illness. You could have better management of it but, you don’t completely rid of the illness. To me, it sounds like he has severe anxiety/stress problem. Now, remember I am not a doctor. I think he should seek professional help to receive correct diagnosis. You can’t make him go if he doesn’t want to. Speak to him in firm, loving tone of voice and encourage him to seek treatment. Tell him you love him and want to see him at his best and that he will always have your full support and commitment. Meanwhile, take good care of yourself. You won’t be help to no one if you are falling apart. Good luck to you and to your husband.