Re: Fashion emergency!
OK, I don't care for the pointed collar shirt under sweaters with the collar showing above the sweater.
What I recommend is a *nice* tshirt underneath. This tshirt would have a round neck, pretty high, and the band around the neck is thinner than on a regular tshirt and the fabric is of a nicer look than a regular tshirt. It could also be a neutral or even a complimentary color, not white.
This gives a clean, simple, and elegant look and is easy to manage.