This truly is a difficult situation. Unfortunatley, these types of things are unpredictable.
What can you do...
1. If your a hard worker and have a history of working 3 jobs, you should be able to find another job. Working part time, you have time to look for another job. Yes, jobs are hard to find, but employers are always looking for good employees who are willing to work hard.
2. Have a garage sale and sell items you don't need. If you'll be moving in with someone, or just renting a room, you won't be needing a lot of the items you have lying arround.
3. If your friends are truly your friends, then you can impose on them for a short period of time.
4 Contact DSS.
5. Contact the Salvation Army.
The SSDI you receive is for your son, not for you. If SSDI is paying his expenses then you should be able to pay for your own.
Added: It seems like some people do not like the fact that I mentioned SSDI is to pay for the child's expenses. These expenses would include a portion of the rent for the space he occupies, the portion of utilities he uses, his education, his clothing , his medical expenses. If the child should leave the home, the expenses would decrease. As far as the portion of spaced that the child occupies, could possibly rented out by a roommate.
I truly hope that the child is allowed to stay with his mother because based on the information that has been provided, it's obviously the best place for him. However, we all know that when dealing with the legal system and CPS, things are unpredictable.