Is it normal i don't explain my problems to others?

I never bring up my personal problems as an excuse for something. Whenever something is going on in my life I usually keep it to myself no matter how much it may bother me. I will explain what I mean better here though.
Currently I am taking care of my uncle who is going through advanced cancer. I have given him my room and sleep outside in a tent. I have been helping him with various things including helping unclog his cathadar every couple hours. I haven't slept since yesterday and it's past 3pm. I don't mind doing this because obviously it is by far worse for him than it is for me. However people often want to know why I may not be on top of other things such as the people I work with. There's lots of other things too. One of my best friends of 17 years commited suicide a couple years ago and I didn't use it as an excuse for bad behaviour. That would have been disrespectful but I wasn't as productive then and was having angry outbursts frequently. Once again no one knew why. My ex girlfriend of 4 years dumped me last year for what seemed random and no reason and most of my closest friends didn't know for months and when they found out they would ask why I didn't talk to them. Some people have even seemed offended I didn't talk to them about my problems. I have diagnosed autism and schizophrenia which I hide very well and not too many people know. I have lots of financial and employment issues and the list goes on but 99% of the world has it worse than me so why complain. I will admit that this is probably why I have a very negative view of people who give up easily or let things stop them.

I have noticed that this seriously effects my relationships with others because people seem to want an explaination for behaviours that may be a result of these situations. I don't get why I should have to explain myself. Why can't people accept that they don't always have to know everything because it doesn't really make a difference why I do what I do.

Next time you see someone you know having problems at work or in relationships take a minute to realize there could be many things you don't know about them.