I've been taking Microgestin 1.5/30 since February of 2009 and I ...

I've been taking Microgestin 1.5/30 since February of 2009 and I just recently started feeling side effects yesterday. I get pounding headaches, feel nauseous and tired. Is is possible to feel side effects now even though you've already taken it for some time. I recently missed a pill because i usually take it in the evening after dinner but forgot to. So I took my the pill as soon as I remembered. I usually don't eat breakfast, can eating the pill at a different time on an empty stomach cause me to have side effects. After the side effects go away, should I start the pill again or switch to a different pill.