How do you know if you have ibs or ibd? i have had diarrhea for a week straight now and it only seems to be getting worse

Diarrhea: for one week needs evaluation for possible infections (viruses, bacteria and parasites) and secondary lactose intolerance. If all the initial evaluations for these possibilities are negative, then I would evaluate for IBD: with blood tests including: CBC, ESR, and markers of IBD

Need work up: IBS (irritable bowel syndrome) is very different than IBD (inflammatory bowel disease). Prolonged non-bloody diarrhea alone would not be suggestive of either. A general practitioner can initiate the work up, but definitive diagnosis may require evaluation by a gastroenterologist.