momz,

If you have been going to this same chiro for months?? and see no improvements - i would not continue going.
Does he talk to you and explain what he is doing for you with his treatments? Does he do upper cervical adjustments and other type of treatments ?
Perhaps try another with more skills and experience?

But I'm pretty sure DDD & rheumatoid arthritis can be hereditary - not 100% so but chances are higher that it could be passed on.

It sounds like you need to find a much better GP and a different chiropractor or take a break from chiro for awhile to see if things improve or what happens.