Popping or crackling noise in the ears is usually due to the issues of the middle ear. I would’ve initially suspected tinnitus, but we can rule that out as of now because there is no mention of nausea.
Tinnitus is commonly accompanied by nausea, unlike the case here. also, since there is no detail about whether it is while swallowing solid food or while swallowing liquids like coffee or water etc, I am going to assume that the issue is happening with all swallowing off and on.
Keeping all those details in mind, the only thing that stands out to me as a probable cause is Eustachian Tube dysfunction, or what we refer to as ETD. The Eustachian tube, as is clear from the name, is a tube. You can think of it as a thin tunnel that runs from the middle ear till the back of the throat.
When we suffer from cough or cold, this tube gets blocked because it gets filled with a sticky thick fluid that we call mucous. Automatically, there is a build-up of pressure in the ear. And every time we eat or drink something, or even when we speak, the pressure gets released and we experience the sensation of popping in our ears.
This popping can also happen if you blow your nose too hard! When this mucous moves within the Eustachian tube, we experience the crackling sound.
People suffering from ETD may also experience temporary deafness, but there is nothing to worry about this. The ear drum or the tympanic membrane is normally flexible in nature. When there is a lot of fluid build-up, automatically the pressure is also more. Due to this, the tympanic membrane becomes stiff and is unable to move when a sound wave hits it. Thus, the sound is heard as muffled and very faint. The higher the build-up, the more muffled the sound is.
However, Eustachian Tube Dysfunction is a long and slow healing process. It does not have any immediate recovery measures, except perhaps that of steam inhalation. A good way is to inhale steam with your mouth wide open so that a major amount of steam goes in.
One should continue to do this at frequent intervals (maybe about twice or thrice a day) till they hear a crackling in their ears or till the nose begins to get runny. It is then that you can understand that the thickened mucous has started to move and that the phlegm will be out of the body either through the nose or through the mouth.
A prudent step here would be to continue blowing your nose after every steam inhalation session, and to continue blowing till you feel that nothing more is going to come out. To help you further with this, decongestants are available in both tablets and nose spray forms.
As it is evident, ETD takes some time to heal. But the good news is that it leaves behind no definite long term effects on your hearing. But just in case that your symptoms persist, feel free to visit a doctor. They can help you with a steroid nose spray and maybe also suggest some other medication to make you feel better.