I Have Had A Cold And Have Had A Block

I have had a cold and have had a block nosed. I have been blowing my nose when I need too but after a while my ear pops and my vision becomes blurred my head feels dizzy and my head drops. It last for about a minute then it stops. But I always feel like I'm going to faint. This happens at least 3 times a day but when it does I avoid blowing my ear unless I need too. Why is this happening and what can I do?