Diarreha and Constipation

Hi. Is it possible to have a normal BM and then have one that's very loose right after it? What causes this? I take one stool softener with a laxative in the morning and another at night. Sometimes I have Chinese tea with senna in it during the day (it's one of those dieters read). I suffer from IBS typically with constipation. But it seems IBS can be constipation, diarreha or both! And I also have severe health related anxiety. What a great combination!