VSL #3 is a prescript
ion-strength probiotic (which must be refrigerated) and much more potent than the OTC probiotics. I believe you do need a doctor's prescript
ion and I'm assuming most pharmacies carry it. I honestly don't know the more clinical specs as to why it's more potent other than the fact that it contains many more billions of the helpful bacteria than the typical probiotics.
But, since my gastro doctor said he didn't think it would help, I would broach the topic by specifying you're not asking your doctor if he thinks it would help, but confirm it would be safe for you to try, taking into account all your current conditions and medications. I've witnessed too many doctors dismiss a medication or treatment method solely because THEY didn't believe it would be beneficial, not because it would have been detrimental to the patient to at least explore the option.
Hope that helps.