Missing periods since 2 months. I do?

I'm working in evening shift from past 2 months 5pm to 2am and by the time I reach home it's 4am in morning. By the time I sleep it's 4.30am. however I still don't get proper sleep and stay awake till 7am in morning as I'm morning person. From past 2 months ( from the time shift got changed), I'm not getting proper bleeding and only day 1 of period will be just spotting.. and it's done. Same happened even this month too. Just spotting on day 1 and nothing after that. My diet include 3 times tea in 5pm to 2am shift, fried home rice ,( chocolates, icecreams, noodles, pastry and some snacks) in office and no breakfast at home. Just tea and biscuit. My shift will be morning shift from next year April month. What shall I do? Any help.