Hi I'm A Little Confused Was Taken Off Nexplanon After

Hi I'm a little confused was taken off nexplanon after three years June 6th. Had another one put in the same day. Kept the new one in until September 9th when I decided to switch to the pill that same day I started taking the pill. Took the pill religiously until the 19th of September. Had two days of bleeding then stopped. Haven't had a period this month at all. Took a pregnancy test on the 21st and it said negative, took one this morning the 25th said negative. Have nausea, diarrhea, gas headaches every day. Abdominal and pelvic cramps. Mood swings but I don't know what's wrong I should have started on the 19th