He should take some probiotics with the antibiotics as well. The thing about antibiotics is they are really great when it comes to getting over symptoms of various conditions and also a good cure but they kill all bacteria in their path including the good ones which are necessary for better digestion. Definitely, advise him to take some probiotics. This can be yogurts, kefir or probiotic supplements.
I have used one such supplement called Flourish Probiotics by Eu Natural and it was really good. Basically, it is a combination of healthy bacteria that helps to support digestion, urinary tract and overall gut health. These healthy bacteria do a lot when it comes to boosting our immune system and fighting off other harmful bacteria.
he might want to try a otc ppi, like nexium or prilosec and see if it helps more, it takes time to heal, months, if no enough he might have to see a dr for a prescription.