What Causes Excessive Weight Loss After Insertion Of Birth Control Implant?

Hi my name is Michele I'm 22 I gave birth to my youngest son Sep.10- 2013 well a few months after that in march 2014 I got put on the 3 year arm in plant birth control I started bleeding a few weeks after I didn't pay any attention to it I thought it was my period so 7 days went by I didn't stop bleeding well I started noticing my clothes was falling off of me so I went back to the doctors on Sep 3 and they gave me a prescription to help stop the bleeding or slow it down. Take 1 a day for 7 days Well it didn't work. I continued loosing weight and bleeding. I went back down there in Nov. And had it removed thinking that's why I'm loosing weight well the same day I got put on the depo shot maybe it would help me gain weight and stop my period for 3 months well its now Jan. And nothing gotten better everything keeps getting worse I get light headed sometimes I feel dizzy I can't breathe my back hurts. alot of stomach pain extremely cold all the time can't sleep.. I went to the emergency room yesterday to get a second opinion and they told me the same thing that the other doctor told me that I have to wait for the birth control to start working in my system its not normal to bleed for a year in scared I have 2 kids.