Wonderful news! You must be so relieved!
It might be worth discussing the use of cystease with your vet. This is a bladder lining food supplement for cats (available from vetuk.co.uk) which is increasingly being used for guinea pigs with long term bladder irritation problems through stones, sludge or interstitial/chronic cystitis. My Nerys has been on it for over a year with great success. It is not a medication per se and won't cure anything, but it can protect inflamed bladder tissue. Please be aware that you will have to keep an eye out for bladder issues from now on.
You can also look for tips for the prevention of bladder stones/grit/sludge forming on this link as well as tips for a balanced calcium : phosphorus diet: http://www.guinealynx.info/stones.html