I've been taking the .10 mg dose of Avaine birth control for about 3 months (this is the 3rd month) and yesterday I had severe cramps and started bleeding, but not as heavy as my period, but a noticeable amount. Today the same thing has been happening but the cramps started earlier on in the day. I was originally taking a lower dose of the same brand but my periods were starting too early so I moved up to this dosage and everything was going fine up until yesterday. Also it is midway through the second week of active pills (I have one more week of pills until I'm supposed to get my period). I'm just wondering if I need a higher dosage of pills or if maybe something else could be the problem. Also, how long should I wait to see what happens before I contact my doctor (if it's just a minor problem)?
The first two months on the higher dosage everything went fine, I didn't have any random bleeding so I found it rather shocking when I started to cramp and bleed yesterday.

Thank you for your help/advice.