I also have IC. You can find a lot of information through www.icnetwork.com. You will find a list of foods along with instructions on trying the elimination diet to help improve your daily symptoms. You will also get a list of things to avoid, keep in mind that everyone with IC has different triggers, however this list of no-no foods are common ones that affect most IC people. VITAMIN C, caffeine, citric acid, acidic foods, aspartame are all things that I have had to give up because they cause increased pain. Due to Vitamin C being a trigger for most people with IC, it is not recommended to take a daily multivitamin. You can, however, take different supplements for inflammation as mentioned above. There are other treatment options, I go for instillations, where I get catheterized and a combination of heparin and lidocaine are put directly into the bladder and held there for at least a half hour. This helps with the flares when you feel like your bladder is a ball of fire or someone is taking a hot arrow head and poking you in the bladder. Feel free to message me if you have any further questions. There are several support groups on Facebook for IC as well as a LOT of information on the IC Network site. You can also look for IC videos on youtube, I know the ICN has posted some with answers to common questions. Good luck with getting control of this issue. Know you are not alone, I also suffer from PFD, vulvodynia, and Lichens sclerosis.
I have been recently diagnosed and am in distress with the discomfort as well. Since this is from inflammation, I am trying to use things that reduce inflammation. I've found that tumeric, ginger, vitamin c, e, b, garlic, mulit vitamin, omega 3 supplements are supposed to reduce inflammation in the body. Some foods as well can reduce such as apples, cucumbers, onions, cabbage, cauliflower, broccoli, kale, beans, etc can reduce. Things to avoid are red meat, processed food, food hi in salt, sugar, caffeine, chocolate, alcohol. Drink lots of water, cranberry supplement, ibuprofen, and over the counter uti pain relievers help.
I have IC too and have been suffering for 3 straight months night and day with a horrible flare. My doctor reduced my Hypothyroid medication in half and the pain went away! Maybe it's your medication.