You should start with one drop and work your way up. 3 drops may be too much for you. However I would not see that giving you a headache. Headaches can be caused by many things. Try to go a day without A314, then try again at 1 drop. Here is a post from Tisha23 that explains how to find your sweet spot, it will be a good guide on how to begin using pheromones effectively. Please read te whole post. 
This is the best advice to follow everytime you use a new product. Also the least followed I think LOL!