Starting a new medication, especially for migraines, is always tricky in the side effects realm. It would really help us to know what medication you were prescribed and what dosage you were instructed to take. Contrary to CIRCA (sorry Buddy), never stop any medication cold turkey without talking with your doctor or pharmacy first. Yes, it is bad to loose time like that, but it may be very temporary, or possibly an interaction with another medication you are taking. My migraine abortive (Stadol Nasal Spray) will make me very sleepy, and sometimes I can't remember whether I took it more than once, or if I have taken my other medications. Usually side effects are temporary, so if you can get through the first few dosages, the side effects are liable to wear off.
Please let us know how things work out.