Although I need to ask a few more questions regarding the rash
and wanted you to explain your problem a bit more but the history suggest two things.
1: It could be Scabies
as you have mentioned in your question that you have contact with the people who are homeless and could be living in crowded places where infestations can flourish easily.
2: although you haven't explained in your question that what sort of job you are doing,like is there any direct or indirect contact with any irritants or solvents? If yes then it could be irritant contact dermatitis
So it's better to see a doctor or preferably a dermatologist
to rule out these two conditions as both of them have completely different treatment and have more or less the same symptoms.
I hope you will benefit from the discussion.
Thanks very much an all the best.