Do I need to Quit my job?

My youngest child will be 2 in July. He has been getting sick really easy and had phnemona not even 3 months ago. I am now a single parent (living with my mom). I had today off of work and had to take my baby to the Dr. He had to get his ears recheached (frequent ear infections that take multipal rounds of anti biotics to clear up and he has asthma that we were rechecking. The his ears are starting to get infected just after 2 days of being off the anti bitotics and his lungs did not improve like the Dr wanted so she sent me to the hospital to get the first of three antibiotic injections. I have to take him back every day for the next two days at a spacific time. I called my boss asap so we could work something out I just needed two hours off each day (which I work open to close by my self 14 1/2 hours each day. And because I told her I needed to be off at this time for 2 hours she blew up because I did not ask and there is no one to cover for me because the are all going out of town. She finally sucked it up and said she would fill in for me and then went on about all this other stuff how she fills in for me all the time and ext. Ok well first off in the 6 months I have been there I have never called in, She sent me home and another girl filled in because my daughter had to go to the ER. I did not even know what was going on till they told me to go home when I got there. The Second time I had PT conferences for my oldest and she filled in for 2 hours so I could do that then another night she send me home 1 hour early because I was peeing blood. I did not ask and that all was over 3 months ago. The big dogs gave me a 90 cent raise for only 4 months. For the last 6 wks I have worked 7am to 1pm by my self 3 days a wk then 2 14 1/2 hour days in a row by my self. And then I can't even take a brake. I am tired of working by my self and not even getting a thank you in return. My child will have to go to the Dr and or hospital almost every day for a while till we figure this out. We are trying not to put tubes in his ears due to his age but we are pritty sure we have to. And after today I do not think they will work with me at work. She stated I can not manage your family and this store. This is my boss I needed time off, there was nothing to involve her with my family. I know I should wait till I have a nother job but with my sons med problems I don't think I could do a job. Dad is not around in any way. My mom does have income so we would not be high and dry. I just don't know what to do. I will not let my job dictate my childs medical care.