It is very important if you have been on antibiotics to take probiotics to rebuild the healthy bacteria in your gut. Antibiotics can weaken the immune system, but probiotics can help build it back up. I take probiotics every morning 15 minutes before breakfast. It is important to take these on an empty stomach! This is when your stomach's pH is closer to neutral making absorption easier.
If you suspect you have Small Intestinal Bacterial Overgrowth (SIBO), then it is important to take a break from probiotics. Attend a holistic practitioner to carry out specific tests and go on a regime to reduce the overgrowth of bad bacteria in the small intestine. Eventually overtime, different strains of probiotics can be used.