Tough it out of find something else?

i started on Thursday and worked yesterday and today, 8 hours each day-so 24 hours in total.I work at Tim Hortons(a Canadian brand coffee/donut fast food kinda place)and i am 16. the pay is good($12 an hour) but there are a lot of drawbacks.For one, the store is always busy. always. the longest time with no one in line was 34 seconds on the dot. and i get the coffee and all the drinks. after peering over the cashiers shoulder, i have to run all around and get everyones orders. then i have to watch the coffee, cream, milk, sugar....with barely any time..and then deal w/ complaints. i know it sounds dumb....but i get really uncomfortable with so many people. it is extremely extremely stressful. and today and yesterday my back has been really hurting me.i'm really not trying to be lazy.i'm also going to apply to some other stores so i'll still have a job.my parents and family tell me to tought it out. but i just absolutely hate the job. i come home crying every day. so what should i do?