Is it "normal" to have common cold or allergies every two to three months? how do you prevent it? will i need an allergy test to find the cause?

Perhaps but: the average adults have about 3 colds a year and thus your problem may not be unusual until the duration of the cold exceeds 2-3 weeks each time and the occurrence is seasonal. If you have a "cold" every 2 months however, then the chance for allergy rises. The presence of itching and lack of a fever would point more to allergy and allergy tests would be the answer.