I was on amoxicillin for a uti. i now have lower back pain, a stomach ache & loose stools. i'm taking probiotics, will they be enough to resolve this?

Time will tell: This still could be the UTI or could be intestinal microbial overgrowth from the antibiotic (even C Diff) or something else entirely. Probiotics are a good idea, make sure they are high dose (8 B CFU), high quality (refrigerated) and optimally would include some Saccharomyces Boulaardi. Some people take these whenever taking antibiotics. If not better after a week or so, better see your doctor.