I am 23 years. i am taking ayurvedic medicine to increase my hunger. recently i caught by common cold and fever. can i continue with those medicines?

Yes: These medicines are not attended by the risks that pharmaceutical-house meds carry -- the latter are far stronger for better and for worse. Unless your practitioner has warned you, continue doing as seems best. Truth be told, the best remedy for defective appetite predates even the wonderful books we call the vedas -- it's getting into an active, fitness-based lifestyle.