It sounds like it could be an allergy too. Try some allergy meds that are on an approved list for pregnancy. Same goes for cold meds unless you'd like a more natural route.
If its not allergies rest, fluids, extra vitamin C, non caffeinated tea with lemon, ginger, honey, etc.
Talk to your doctor at the next visit because sometimes sudden onset of cold like feelings is just another pregnancy symptom and they dissappear after giving birth, but you could also actually have a cold or like above, allergies. Depends on your location as well because with where I'm at in ohio the weather is fluctuating so much that it makes me feel sick one day and great the next.