Breast soreness that comes and goes?

Question for all you moms on your 2nd+ pregnancy: is it normal to have breast soreness that is really bad one day and then hardly there at all another day, or is it usually pretty constant?

I'm 5 weeks and yesterday my boobs were so sore that the pain woke me up. But the end of the day and this morning they are much less sore, just a little tender when I press on certain spots.

Is this something I should worry about? I'm trying to to read onto every little sign, but it's not going well, haha. Husband thinks it's probably ok...