Cranberry Juice
If your guinea pig has recurrent UTIs, try offering plain unsweetened diluted cranberry juice. Antibiotics are required to cure a UTI but cranberry juice may interfere with its development, cutting the incidence of UTIs in half.
Use only unsweetened, natural cranberry juice. Syringe feed or place in water bottle. Change bottle containing juice at least daily and preferably twice a day. Plain unsweetened cranberry juice is quite strong and bitter in taste. Dilute with water. Do not use human cranberry drinks sweetened with sugar, apple juice, or other juices.
Check your local health food stores for this product.
https://www.guinealynx.info/uti.html#top Best I can offer. Sorry, guess you read it many times before.
Your goal is to keep your guinea pig as dry as possible to prevent infection.
Keeping the butt hairs of a long haired guinea pig trimmed may help.
Change bedding more frequently, especially areas that are wet (spot clean).
Look into polyester fabrics which reportedly allow the urine to drain through but stay dry.
Some people use a safe plastic grid flooring like Envirotiles (different from wire flooring) to keep the guinea pig from direct contact with urine.
UTIs are generally treated with a safe and effective antibiotic like Bactrim (trimethoprim/sulfamethoxazole) for two or more weeks. Many guinea pigs require longer treatment to clear up the infection and allow the bladder walls time to heal. Call your vet immediately if bleeding recurs after antibiotics are stopped. If your vet did not take an x-ray and the original signs you observed are still present while on antibiotics, be sure to have an x-ray taken immediately.
Has Irie had X-ray? Might be worth looking into. If he is laid back they might be able to do it with no sedation. Look into Cranberry juice from health food shop. And Envirotiles what ever they are! Good luck.