You have received some excellent advice. I want to comment about your 3 1/2 year-old. Talk to her and ask her to help you out.
You don't mention where the arthritis is (hands, back, neck?). For the back, the first thing she can do for you is only give you hugs when you are sitting on a chair. Ask her to never _pull_ on your arm (like when you are holding hands).
Ask her to do stretches and exercise with you! If you see a physical therapist, ask about ways to handle your pain when your daughter wants you to (oh, say) pick her up, kneel down on the floor, etc, as well as ask how your daughter can get involved with things that will help you!