Oh dear, I really feel for you, it must be so worrying to see those bumps on your little one, especially at just 3 weeks old. Please bring baby to see a doctor as soon as possible, because blisters on a newborn that young need to be checked by a professional right away and this is really not something to wait on. You are doing the right thing by reaching out, but a doctor needs to see those bumps in person to know what is going on.