Is it really true that I will get headaches and joint pain if I don't follow the traditions of chinese confinement?

Not really. I didn't follow strictly to the rules. I didn't wear socks, walked around most of the day, bathed my baby and even had ice cream during confinement. My joints did feel numb after being in contact with cold water, but this lasted for less than a day. I'm feeling okay now, with no after effects.