When I was a baby I had a fever spike so high my mom describes me as "twitching", which I think may have been a small seizure instead of the full-blown ones you're experiencing. I'm pretty proactive on fevers because of this, and because of exactly the situation you're describing: you end up being terrified (by a terrifying occurrence: I've witnessed grand mal seizures and it is truly terrifying) and calling for help and then can really have that backfire.

For what it's worth, I've found the infant ibuprofen is quite a bit more effective than Tylenol and also lasts twice as long, so a dose at bedtime carries them through the night when they can do that sudden fever spike. The other benefit of the ibuprofen is that it also is an anti-inflammatory, so any sore throat or other inflammation coming along with the virus gets some relief in the process of bringing down the fever. I will generally let a low grade fever progress in the hopes of killing the virus, but nighttime is tricky and I usually dose the kids to keep the fever in check and also to help them get a deep night's sleep (because they're more comfortable) in hopes of letting them heal quicker.