I have a friend who was on the shot, and every time she was due for another shot she would get pregnancy like symptoms. I know you said you stopped it in may, but maybe your body is just getting use to not being on it. You were on it for two years, thats a long time and you body was use to having those shots in you. I would just ride it out and see what happens.
Also, if you (which I have done plenty of times) stress your self out about it, you will give your self these symptoms. Its called a "phantom pregnancy". I do it all the time, if I missed a pill or something, I will stress myself out, and every little thing I will say is a symptom, just becuase I want it to be. You know what I mean? Well anyways, you just have to see what happens and keep in touch with your doctor if you notice anything too irregular.
Good luck, and keep us posted!