Is my body reacting like this because of my birth control pills or because of my weight loss?

I always been irregular all my life and overweight. I was told because I'm irregular is because of me being overweight. Well, I had a gastric byp 7 months ago and already lost 120 pounds. I'm still considered overweight but not obese. A month before surgery I got on birth control pills as advised by my doctors to avoid pregnancy after losing weight. I have been taking them religiously since then. The pills I was given to take is Seasonique. Ever since I started them I have had nonstop spotting or bleeding and here recently I've started to get cramps even when I'm not taking the "yellow pills". I was told the spotting is normal and will subside over time. I don't see it getting any lighter or even stopping. I have to wear a pad all the time 24/7. The type of bleeding I have is very dark brown and here recently I notice blood clotting coming out when I pee or on my pad. What do you think this coud be? Is it because I lost so much weight? Is it the pills? I feel like I'm getting worse because now I'm getting cramping and discomfort right in the center area of my pubic area. Not on the sides like normal pms cramping but in the center it feels like someone stabbing me. I made an appt. with my gyno. for next week but I'm just wondering what everyone elses thoughts on this. Anyone else had surgery and took these pills have similar issues? I tried searching online but can't find any links to the connection of my issues plus the surgery. Thanks in advance. =)