What Causes Severe Fatigue And Excessive Weight Gain?

Hi, I am a 31 year old woman. I over the last 6 months have been fatigued without any changes in sleep or activity, I have gained weight rapidly, my abdominal and pelvic area constantly feel bloated and full, and often very very painful there. I am diagnosed with PCOS, but I don t believe it is related as I am carefully following a diet and exercise program that adheres to the pcos lifestyle ( low carb/low glycemic). I am curious if I should be concerned about the painful pelvic area, the unexplained sudden weight gain, the fatigue and such. I had blood work done 6 months ago right when the pain and weight gain started, thyroid test came back normal. I am insulin resistant but other than that my regular bloodwork was fine.