Hi, welcome to the forum. I have gotten those multiple times, yes. I never had them up until IBD came along, either, but then I started getting them regularly once I got sick, so I presume the two must be related in some way (my GI seems to think so as well but we have no solid proof).
Mine seem to be different each time as well which is very freaky. Like you said, I worry that I'm about to have a stroke or something when it comes on. Mine only happen on the right side for some reason which is the main way that I can tell it's a migraine and not something more sinister (although it's still worrying and freaky for sure!). Once it was like, you know that old Windows 95 screensaver where it's a colored ball that bounces around and turns into a cube and then back into a ball again? It was almost exactly that in the peripheral vision of my right eye - so weird. Other times it's been as though someone turned on the lights but only on the right side, or turned up the clarity and contrast so that my vision was extra-sharp, but again, only on the right. These visual auras are usually followed by a headache with sensitivity to light & sound - the headache usually comes on about 10-15 mins after the aura starts, but once it took about 4 hours between the aura and headache. So I never really quite know what to expect!
Has your doctor suggested anything to prevent the migraines? I take 25 mg amitriptyline each night before bed. In higher doses, ami is an antidepressant, but in lower doses (10-25 mg) it has different effects. In those lower doses it can help with insomnia (it helps me fall asleep and stay asleep), it can help in some cases with chronic pain and with digestive issues, and it can help prevent migraines. Amitriptyline prevents most of my migraines, so I hardly ever get those visual auras anymore (I only get them now when I have a migraine trigger, such as caffeine). Might be something worth looking into for you. Good luck!