I was on depo for five years prior to now and never had a problem. I was off it for a few years and am now back on it. I have the same problem, but only in the last month of the three. My doctor has put me on some low dose estrogen pills this time and had me get my second shot a month early last time, maybe check with your doctor and see if you could try this? If your doc lets you know why or what exactly this is please let me know! Good luck!