I have been having migraine attacks for the past 4 weeks, after several test by my gp, I was prescribed crestor (rosuvastatin) for high cholesterol. Any help pls?

Back to the migraine. To stop the headaches, maybe a triptan, and to prevent the headaches, many choices either prescription or otc, so discuss with a headache specialist. Glad your cholesterol is getting controlled, but Crestor (rosuvastatin) has no effect on migraine, good or bad. Lastly, why do you take gingko, discuss that with your doc also.
No connection. If you have migraines, lowering your cholesterol with a 'statin' is unlikely to have any effect - positive or negative. Depending on how high the cholesterol, taking Crestor (rosuvastatin) may be a very good idea, but this is an unrelated issue.