Hi Juli,
What sort of chemo are you on? On TCH (Docetaxel, Carboplatin and Herceptin) I was given little white Dex tabs for three days: I had to take one the day before my chemo and one the morning of my chemo, and one the evening after my chemo. And the following day too. They gave me an infusion of more Dex at the start of the chemo infusion process.
But they have different Dexmethesone regimes at different places for different chemos
I also had the phone number of the oncology ward, and if I was in doubt on anything I rang and spoke to the best-informed nurse, with a number for day and another for after-hours cos they worked 24hrs.
It sounds to me as if they have either not given you these contact details or not encouraged you to use them to check on anything you are not sure of.
I would suggest you get them at your chemo today, and write them somewhere you won't lose them, and even at the risk of feeling you are making a nuicance of yourself, ask when anything concerns you. Talk to all the nurses, find out who are the senior ones with most experience who can answer your questions well.
But for now, can you ring the ward and speak to the senior charge nurse about your dex and when it is given and what to expect? then you know and don't need to be concerned.
best wishes.