I never ride in the drops...just so you know that it's not required. It does sound to me like perhaps you are stretching out too far. I'd suggest going back to get a second fitting--your body has changed alot since you started and your bike fit might need some tweaking.

Great news about the weight loss! Get working on that core. You don't need to wait. Sign up for a reputable Pilates class, you won't regret it.