In a word, yes. Hyperthyroidism is the first thing that comes to mind. As a thyroid cancer patient, my experience has been that there is a strong correlation between thyroid dysfunction, rapid weight fluctuations, and mood instability.
Unfortunately, resolving these issues typically involves more art than science. Blood work alone is unreliable. I cannot overstate the importance of taking the time to locate and consult with a rock star endocrinologist - not a good endo, an amazing one. They are few and far between, but do the work anyway. Primary care doctors are well intentioned, but they often lack the specialization and nuance necessary to adequately treat hormonal imbalances. As a result, you need second opinions, third opinions, forth opinions, unconventional opinions: naturopathic doctors can be great with hormonal issues. You are an individual, and by default, so is your hormonal system. Where you feel good in relation to your medications is somewhat subjective.