I love botox. I get significant relief from it for the 9 weeks after they give the injections. I'm on my 6th round.
The thing with botox is that the first round sometimes does nothing. Is this your first round? Second round is usually much better and it can take up to five rounds (each strengthening) to tell how well botox will work on you... it's different for every person. If your eyelid drooped (it will go back to normal after the three months when the botox wears off then the botox spread into the muscle between the two they're targeting on your forehead... which means it may have also spread away from the area where it will dull the headache in that area (this is just according to what the girl who does my injections tells me... I am not a doctor.)
Also, if you have any issues, be sure to tell your injector because they can sometimes make adjustments for subsequent rounds. Like I had severe neck pain and double vision the first time and they had to adjust where they gave the shots.