<<Disclaimer: Verify this information before applying it to your situation.>>

Apologies for the delay.  The following is a summary of the products
recommended for travelling celiac athletes who also have to pay
attention to doping regulations:
1.  Always check your banned substances handbook from your sport
2.  PR Bars:  have 40-30-30 balance of protein, carb and fat
3.  Call the folks at stokes  http://www.stokesrx.com   ....
They easily whipped up a nice batch of GF alka seltzer cold
plus, and I had it in my paws in 3 days.
4. Try pure Guaifenisen (the main ingredient in cough medications, but without
the sugar and artificial ingredients). It is a mucous thinner for which you
may need a script, but I got it on the web without a script.
5.   homeopathic remedies?
6.  I love the antihistamine effect from Red Apple Herbs #40, the one
with the black lid.  No grogginess and no side effects.  Goes to work in
about 20 minutes, but only lasts for a couple hours.  And make sure
she's completely off dairy, as dairy compromises an immune system to the
point of reacting to allergens.
7.  I like the gf GeniSoy soy protein bars, apple spice yogurt coated
ones.  If the travel isn't over 24 hours, I bake some red potatoes and
wrap them in tin foil with some seasoning, then refrigerate and keep
them in a small cooler.   I bring those taters hiking as they are a
great source of energy.  Also, packets of E-Mergen-C are a good source
of vitamins, minerals and electrolytes.  Just add to about a pint of
water and drink over a long period, maybe an hour or so.
8.  Have you tried small cans of shoestring  potatoes with pop-top lids.
 or Cans of powered bean soup?