Hi
Welcome to the MedHelp forum!
If you have missed periods, then take a pregnancy test and see. Other than IBS or spastic colon you could be suffering from Celiac Disease/Ulcerative Colitis/ Crohn’s disease, H pylori infection, diabetes, food intolerance, malabsorption syndromes, constipation, gallbladder and liver problems, pancreatic dysfunction, or taking a diet rich in sulfites. Cancers of the gut and in female ovarian cancer too could be a cause (less likely in your case). It would be wise to rule out PCOD as well.
Since I cannot examine you and know other related conditions you may be having, nor is a detailed history possible on net, I have listed the various possibilities that should be looked into. Please consult your PCP and gynecologist to run tests and examination to clinch a diagnosis. Take care!
Well what your describing are common symptoms of pregnancy in the first trimester. I say you take a home pregnancy test and see the results and also contact your doctor to be sure. I hope i was alittle help and goodluck ! :)