Just found this forum! I am now at just over 10 months post-op for retrosig removal of AN, ~3cm. I am SO interested in the Allegra-D results you have had.
My doctor has put me on Indomethacin (Indocin) a NSAID that some people take long-term for arthritis. I take 50mg 3x daily, basically every 8 hours, with food. If I am very late or miss a dose of this the headache is still incredibly bad! I have described it as an ever-present headache that needs the anti-inflam. meds to quiet down. This works for me, but barely, and I am totally reliant on the Indocin. It's also depressing since the dr. keeps telling me it will get better over time and it hasn't. I also find that caffeine helps with this as well.
I might try the Allegra-D, but I can't imagine dealing with these headaches without the Indocin right now.