How To Treat Muscle Twitches In Abdominal Area Towards Pelvic Bone?

I am a 23 year old female. I have gained weight in my abdomen in the last few months and it is becoming uncomfortable to bend over. I have also been feeling what I can describe as muscle twitches in my whole abdominal area under my ribcage to my pelvic bone from time to time, sometimes more frequently then other days. I am worried I have either some illness or thyroid problem because I don't feel I should have this much weight on me located on my stomach.