If your belly is expanding, then my guess would be that the dots are sort of part of the skin stretching - I've had that before. As for the shoulder - beats me. All I know is that with a suppressed immune system during pregnancy, skin can do some funny things. Could be some sort of weird rash, but I don't know what I'd do about it apart from keep it moisturised if it's dry and keep an eye on it. If your GP doesn't know what it is... The body can be a random thing during pregnancy.