Rhode Island Red Hen Not Laying Properly

[RedBreasted]

So I have a RIR hen and she is acting fine. But a couple weeks ago, she lay like 2 or 3 a week. I heard that these breed are excellent layers. But when she lay a huge egg is always a double yoker but then she change into small and never gotten big again. But all her eggs have white or brown specks on them. 2 of her eggs have I grab have small and medium side calcium spots on them. I didn't mess her up when she is laying nor giving her bad chicken foods for her diet and the water, I change daily. My 2 other chickens lay normal but I don't know why she is acting up this way. Should I be bringing her to a vet? Well my Buff Orpington hen, she lays like 5-6 eggs a week and I heard that they can only lay 3 eggs a week. (Sorry for the poop, I'll be cleaning them today! You wouldn't believe how much poop can 3 hens can do!)