It's really almost impossible to say whether it would be related to your drinking or not, but 3 weeks is still very early on for your body to recover. If you haven't had a physical or a checkup since you quit that's not a bad idea, you could certainly mention this to your doctor.
There are a whole host of problems drinking can cause us, and many of them will improve over time after we quit - but also remember that many of us had bad habits associated with our drinking too: Poor diet, lack of exercise, not enough sleep, etc. While the act of cessation of drinking certainly helps, we need to address all areas of our health to make sure we're doing the right things.