I m having many symptoms I ve never experienced before and currently having tests done to figure out the problem. My symptoms are as follows: excessive weight gain, extreme fatigue, and certain days I also have these symptoms happen and last for hours, which are heart flutters, numbness and tingling, burning sensations through my upper body, shoulder pain, and dizziness, nausea, vision blurs, mouth and tongue feel weird, and very disoriented. What could this be?