I have had a TIA and a stroke, which they officially are calling a "complicated migraine" but I still have lingering symptoms, 7 months later. So I've done quite a bit of research and am now working with a neurologist and a neurosurgeon to know what the heck really happened, if possible.
If your TIA is related to lupus, it could be part of antiphosholipid syndrome. Basically, another autoimmune thing that causes problems with blood clotting. That accounts for the temporary blockage of blood to the brain. Your rheumy can do a blood test to check for that antigen.
According to my neurologist, the answer to preventing future episodes is fairly simple - daily dose of aspirin. It helps keep the blood thinned out. I was taking 325mg, but after several months my stomach couldn't take it anymore. I'm back down to just the baby/healthy heart dose - 81mg. It is a huge, huge relief to know I can do something so simple to prevent something so disturbing.
I definitely suggest that you talk to your rheumy or someone about looking into this possibility.
Hugs, and may the force be with you
"What a friend we have in Jesus, all our sins and griefs to bear. What a privilege to carry everything to Him in prayer." (Old Rugged Cross)