First, congratulations on your marriage.
I see nothing wrong with telling your husband when he gets back from the trip and asks how you been while he was away and you mention you had a bit of the stomach flu.
That is not weak and I agree limit what you tell your mother or she will dictate on your marriage life. Your husband is your partner and if you canít share your life with him on how you feel or what your thinking what is the purpose of marriage?
Your mom may be old fashion but tell her you are now a grown woman and you will decide what you tell YOUR Husband.