Pelvic infections, depending on the strain of microbe, can be serious, so I would think that it is probably wise to take them under your doctors advice. It is important to finish the full course of antibiotics, because stopping halfway through the desired length can put you in a tough spot- not all of the "bad" microbe can be killed, but plenty of the "good" microbes will be, so it can actually cause the infection to worsen.

Taking probiotics WHILE you are taking antibiotics may do a little bit of good, but chances are the antibiotic is killing a lot of the strains that you are taking in. That being said, I always think it's better to just keep taking them, just in case it helps. The most important window for the probiotics is immediately after stopping the antibiotics- you want to get a jump start on colonizing your gut with good bacteria. Fermented food is important during this time, because it offers such a diverse microbiota that it will maximize colonization. You will be more susceptible to different infections (the ear is a common one) immediately after the course of antibiotics, so just try to take it easy, get all your good bacteria, stay hydrated, and don't push yourself.

Antibiotics, when used appropriately, can be really important in preventing much worse infections- it is wise to keep in mind that they are a life saving tool when the need arises. There are some things they should obviously never be used for (acne, farm food), but they can be a useful part of modern medicine.

Can you eat naturally fermented vegetables? What about ginger tea for the nausea?

While you're on the antibiotics and not feeling great, I think your number one priority should be trying to eat the best overall nutrition to help you get through this in as good condition as possible.

Once you're done, your probiotics will then do their best for you but don't forget they're just like us--they need to eat. A healthy mix of meat, vegetables (ideally both fresh and cooked) and fruit will be just as important as taking the probiotics. It won't do much good to swallow lots of the good kinds and then starve them.

If you can tolerate such, "lively" kombucha or water kefir are 2 of the most powerful probiotic food/beverages. If you decide to try either of those, because they ARE powerful you need to start with very small doses--such as a teaspoonful once or twice per day for 3-4 days, then a tablespoon for another few days and then gradually increasing quantities.

Eating more vegetables is a great way to help with the stomach issues. Probiotics are definitely a good start and one of the most effective ways to fight the antibiotics. If you are taking over the counter probiotics you may wish to find a more potent strain. CP-1 is very potent probiotic item and if you want to replenish the good bacteria that the antibiotics killed off I would start there.