bubbles in uterus?? depo?

Hey everyone. I'm currently on the depo shot for my second month now and haven't had my period since august. However ..... I just felt a ripple of bubbles on the left side of my uterus and have been feeling pain in that side only. Along with nausea. Can someone help me I'm really paranoid right now every test I have taken has been negative and I don't know if it's because of the depo giving me false negatives ?