Sigrid: I was half asleep when I posted you last night. It sounds like you have a lot going on - managing a chronic illness, working full-time, recurrent sinusitis and fostering your two young nieces. You may want to look into Social Security disability forum since you don't have disability insurance.
I found continuing to work full-time and being a Mom was not doable. I was getting recurrent hives, chronic strep with tonsillectomy and recurrent sinusitis. Now that I don't work, I am managing my disease much better.
A strong willed 5 year old is hard to deal with. Stay consistent with your discipline and give lots of positive reinforcement and attention to your niece. The house chores shouldn't be a priority. Just stick with cooking healthy meals and sanitizing kitchen and bathrooms. Let the other chores go.
Hope you get your hearing back. Please keep us posted.
Shari