Why does teething hurt?
Your baby's teeth started developing in the uterus, when teeth buds were formed in her gums. As her teeth develop, they push through her gums, a process which can cause irritation, pain and swelling.
While pressure seems to relieve the pain, sucking causes more blood to rush to the swollen areas, making them particularly sensitive. This is why some babies may temporarily reject the link breast or bottle when they are teething.