Stopped Taking Cerazette. Missing Periods, Feels Sick, Headache, Frequent Urination, Pregnancy Test Negative. What's Wrong?

i was on cerazette ( pill tablets) since july last year and recently came off these around 10 weeks ago, and since then ive not had a period, i dont know if my body is trying to get back to normal but i did a test around 3 weeks ago which came up negative, but the last week ive had random bursts of feeling sick, frequent headaches , strange taste in my mouth, and getting bad heartburn (which makes me feel sick too) also finding myself having to have a nap during the day ( i used to do this as i have a underactive thyriod) and having lots more white/clear discharge (sorry TMI) and peeing a lot, like 4 times every hour maybe even more! i did a pregnancy strip test this Afternoon which came up negative. why am i feeling like this?