I have a 29 year old son and for the past year, I have been doing a lot of work for him at his shop.(He has a welding and fabrication business). Most of the work I have been doing has to do with maintenance and upgrade and renovations of the building. I do not have any other employment as I suffer from PTSD and have a difficult time working outside a "safe zone" for myself. My son doesn't seem to think he has to pay me for my efforts and when he does it is a mere pittence. I do have expenses and have gone as far as to get Social Services for a time to get by.
My question is this. Why would my son not pay me at least enough to take care of my basic expenses when I am there doing whatever he needs 40-50hours a week? I have explained to him that I do not expect a huge salary but at least something each week to pay the basics,, groceries, telephone, gas in the car, etc.
I have been turned down by SSD because I can work. As I stated, I can't work in a "public" environment.

Just because your disabled, and having employment issues, is no reason to be stiffed into providing cheap labor. Go to your health and human services department, in your town and speak with a case worker, and get the aid you need, and stop letting your son take advantage of you.

Like Tal says , he is taking advantage of you. Look after number 1 and that is you. I'm sure you've spent enough of your life looking after your son.

There really is only one solution for situations like this, and that is for you to work elsewhere and be 100% unavailable to him. Then he'll possibly come to his senses and realize you're worth more (because YOU finally stand up for that fact) and will offer something for you to come back.

Or he won't. Either way the slavery will have ended.

The real problem needing resolution isn't his cheapness, it's your willingness to take it. Posting queries here on the forum is a good first step, but it's far from useful if in the end you don't end up finding something else "private" you can do to make a living, and I mean YESTERDAY.