I'm so sorry that your wife is having discomfort around her port site! I hope that she starts feeling better soon.
I wanted to add to Mary's post which has such great advice, and mention that the nurses should be able to flush the port easily, and withdraw blood without difficulty. If the nurses are not able to get blood "return", or have difficulty pushing saline in, fluids, etc. then this should be mentioned to the oncologist. Sometimes a procedure called a portogram is performed by a radiologist to inspect the port for functionality. This is generally done if the port seems to be malfunctioning.
If there is any burning, stinging, or outright pain during or after chemotherapy administration though, this should be investigated promptly.
Karen D. BS,RN,CHPN
This post is not to be taken for medical advice, and is merely my opinion. Please always consult with your physician if you have concerns.