Do you have any hearing loss
and any ear discharge
. Have you been subjected to a thorough ENT evaluation by your Doctor. Usually crackling sound could be due to fluid collection in the ear. Usually if there is no hearing loss and ear discharge, there is less chance for perforation of ear drum. The allergies can cause block in the tube causing retaining if ear fluid. You can apply nasal decongestant drops, 2 drops in each nostril
under medical supervision while lying down in supine position. If the ear feeling gets relieved then it could be the reason as quoted. Avoid going near smoke, dust, pollen. Use handkerchief in such situations. Consult your Doctor and get a proper solution for your allergies.