I'm sorry you don't have anyone to help -- where are you located? Maybe there is someone here who lives where you are & is willing/able to help out? Do you belong to a church or any kind of group you can call? I would say now is the time to ask for any help you can get so you don't get any sicker. As we all know, the mind-body connection is strong and stress can make everything worse. You might call your mother-in-law anyway and see if she is having a good day or has friend to call. If you end up in the hospital then you'll need to get that help & your body is telling you it needs your attention now.
When you are feeling better, you might want to find a new moms networking group -- my friend who is a single mother has gotten so much help from other moms she knows & all woman need help at some point with a baby. It's just too much to do alone.