Hi welcome to the health care magic You have received radiotherapy for thyroid cancer.. Radiotherapy can lead diarrhea as side effect... Alcohol drinking also can lead functional bowel problem... Hence try to avoid alcohol and take healthy foods with green leafy vegetables and fruits.... When having constipation if needed isapghula husk with milk like mild laxative can be taken.. If possible Avoid use of milk of magnesia... For diarrhea if needed racecadotril like antisecretory drug prescribed Stool examination done while having diarrhea and fever associated antibiotic might prescribed Without consulting doctor don t try medications by own Take care Consult physician for examination