Oh my word. Who prescribed you Imitrex as a daily preventative? That's not okay.
I was on Imitrex injections, double the normal per month prescription. That was only 12 per month, IIRC. My doctor said, "I know you need more than that, but we don't if it's safe. I'm so sorry." This was during a 3 or 4 month stint of being bed ridden every day and finally having a migraine induced seizure. Even then, it was not okay to take every day. Perhaps the injections and pills have different rules. But you need a second opinion.