Hello ma am and welcome. Pregnancy is less likely, but it would be wise to go about a home pregnancy test using an early morning urine sample at least 2 weeks from the suspected date of conception, or on or after the second day of a missed period. You could also visit a doctor in about 3 weeks for more conclusive results on pregnancy. As for what this could be if pregnancy is ruled out; you are exhibiting symptoms of a hormonal imbalance which could be brought about by various factors like infections, birth control, contraception, stress, sudden weight gain or weight loss, other medications, medical conditions, etc. As you have a recent history of the depo shot, this could be the cause but this will have to be confirmed so I would recommend a doctors visit. Best wishes.