If you can send someone to a shop that sells them you could try; Elderflower, Limeflower, Rose Hip and Echinacea (root) tea.
If 4 are too many to buy Yarrow and Echinacea would be good. A steam inhalation of yarrow really helps to unblock sinuses too... that is if you can inhale it!
If you are eating then lots of veg obviously, especially onions, garlic, ginger, thyme, rosemary, oranges and lemons. Lemon and honey in hot water is nice.