<human>: Just looking for some other people's opinions and perspectives regarding this work related dilemma. Thanks in advance.

A year ago I had to quit a job because anxiety and my mood issues were getting in the way. I took a long break unemployed and not going to school. I kept trying to apply for jobs and got rejected several times.

A few months ago in December I finally got a job. It is a retail sales associate position. However during that same month I got an interview for another job, as an art teacher. I got hired, but neither job's managers are aware that I work two jobs. 

Lately the manager for the retail store hasn't been great with following my availability. I keep getting scheduled for shifts that collide with my school schedule (started going to school in January) and even collides with my other art job's schedule.
It's giving me a headache having to say, I can't work because of class, and trying to decide if I should tell them why my availability keeps changing and why I can't work certain shifts despite being scheduled. My manager told me I have to find someone to cover those shifts but I don't think it's right how she never approved of my changes in availability months and weeks prior.

Should I mention my second job? I am not sure how a manager would feel. I think they wouldn't like that, but not sure. 

Have any of you been in this situation? How would you handle it if you were me?

Summarize the given text in a few sentences.
<bot>: Work schedule is getting messy because I have two jobs as well as school. Should I notify my managers I have another job or keep silent?