As a eNT surgeon I help u on this kindly share ur history and treatment u took till now then we can connect most common causes being:
1: mandibular ankylosis
2: sub mucosal fibrosis
3: infection of throat
4: infection of mastoid area
We u reach a conclusion by good history
Next Steps
For further clarification, complete evaluation, correct diagnosis and treatment and prescription feel free to consult me on this PRACTO APP. Stay safe and take care of yourself