Your pharmacist knows more about drug interactions than your specialist (or should). They also keep many things behind the counter (like 325mg iron tablets) so if you can't find what you're looking for, ask them. A lot of users on the forum take probiotics (I haven't noticed them to do anything but that's just me), vitamins (I take a women's prenatal muti cause it has a lot of folic acid even though I'm not pregnant) and fish oil (I don't take it but I haven't heard any harm only good from taking it. It helps your heart and other things even if it did nothing for Crohn's which I'm not sure if it does or doesn't). You should really have blood work done to see if you're low in any nutrients to begin with and keep having blood work every now and then to make sure you're within normal limits. If you're not absorbing properly than or vitamins wont have much of an impact (I don't absorb B12 or iron very well so I get a B12 shot every other month and take 650mg of iron nightly with a little extra from the multi). When you get that new insurance (if you find one or find a free clinic to go to) be sure to look into a new doctor right away, one that will take you seriously.
