Sometimes i have a sudden pain in my ear the doc did not recognise any problems can it be allergy?

Itch not pain: Allergy is generally associated with itching (eyes, nose, ears, throat, skin) rather than pain. Significant nasal congestion however can lead to eustachian tube problems creating an imbalance of air pressure in the middle ear leading to pain, fullness, popping. If there are nasal or breathing issues, this could indicate allergy type issues and should be investigated.

Probably not: Allergies cause itching/swelling/redness, not pain. May be a jaw joint issue. Ask your Dentist to evaluate.