How long until one shot of Depo wears off?

I've been to many doctors who find it hard to believe I am still suffering from extreme side effects from Depo Provera, the birth control injection. I got the shot mid December, and since then my life has been reduced to the confines of my own home. I used to exercise 6-7 days a week and lived on my own. I had a personal trainer and a strict diet. My symptoms such as fatigue, dizziness, tight, knotted and stiff muscles, constipation, etc. have taken away my freedom, independence, and will to live. I have been on the brink of suicide from the hopelessness. No doctor can help me in alleviating symptoms or determining when I will feel normal again.