Hi welcome to Health care magic forum. Your description suggests the your feelings are due to drowsiness
of the cold
medication. If it is due to hit there should be , collapse, vomitings, giddiness, etc.
Any how it is better to consult a physician, for confermation of the condition. By having C.Tscan he will decide whether there is any effect on the brain.
Besides i advise you to follow some diet recommendations as ,Take more of green leafy vegetables, pulses, sprouts, fruits, juices, and non vegetarian foods, etc.
Wishing for a quick recovery and thanks for calling health care magic forum.