1 Poison ivy, poison oak, and poison sumac are plants than can cause an itchy rash upon contact. 2  A substance called urushiol, found in these plants, causes the rash. 3  The rash is not contagious.  The rash usually disappears in one to three weeks.
Common factors that can cause clogged ears are wax buildup, air flow blockage to the Eustachian tubes, pressure differences in the middle ear, and cold and sinus problems. Clogged ears can affect people of all ages, but is most common among children, especially when they have colds.
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.