My ear keeps blocking and needs popping to unblock but crackles?

Eustachian tube. Eustachian tube dysfunction. Often seen with or after allergy exacerbation/ cold / sinus infection. Keep popping your ears several times a day, try saline nasal spray or rinse, otc antihistamine/ decongestant (e.g. Claritin+/- d). You may also try afrin spray for a couple of days only. See an ENT doctor if this doesn't help.
Allergic rhinits? Uusally this is a symptom of allergic rhinitis or eustacian tube dysfunction. You can experience this after a viral illness and usually is treated with intranasal steroids and otc anti-histamines. See your doctor to determine if there is fluid behind the tympanic membranes.