What Causes Persistent Ear Congestion Despite Taking Medication?
not very likely
sudafed is a decongestant so the expected effect is congestion relief. If it does not work as expected then there is no reason to take it. The rebound effect usually occurs with nasal preparations. The 'usual' dose becomes less effective and it has to be taken earlier and earlier for the same effect to occur. This usually happens after a week or so of continuous usage. The oral preparations are less likely to cause it.
Perhaps your doctor can prescribe local corticosteroids if there is excessive inflammation and help with the plugging.