If you're comfortable, it might be helpful to talk to your boss about what you're experiencing. You can ask for help like working during shifts that are a little quieter or having a plan for how they can help if you are getting overwhelmed. Legally, you can ALWAYS ask for reasonable accommodations at work. The boss isn't required to give them, but you can ask and negotiate to figure out if there's any changes that would make your work experience better. Of course, if this job is just not going to be good for you in the long run, it's never to early to start looking for something new. But that can take a long time and lots of work so try your best to find ways that your current job could be made more tolerable in the mean time!