Soy isoflavone extracts and supplements are available as dietary supplements without a prescription in the US. These products are not standardized, and the amounts of soy isoflavones they provide may vary considerably.
This can sometimes be caused by allergies, infections, and even tumors, but it is often simply something that some people have due to their anatomy (ie, they were born with a pre-disposition to this problem). Sometimes, this clogged feeling in the ear can be a trigger for headaches. As you know, headaches can come on from almost any cause, and some people will have different things that are triggers for these headaches to start. Continued ear pain, hearing loss, and dizziness would all be potentially worrisome symptoms.
Plugged ears can be caused by rapid changes in ambient pressure. This is, again, a result of the auditory tube. Along with the eardrum, the auditory tube helps to equalize the pressure between the middle ear and the outer ear. This is why your ears can feel plugged when you are driving up a steep mountain or taking off in an airplane.