hi i think what you was having was near to a fainting fit have a good read through this link sounds from the way it reads it could help you. <link> just copy into google to the www. to open and read. but not to sure it was down to you sinus's being blocked up sounds more like low blood pressure. good luck
very sudden extreme dizzy feeling as though spinning which drained my energy and made me want to vomit could be sinus? . recently had a severe head cold that lasted for more than a week and started acting like sinus issues before leaving. felt fatigued this morning but better after starting the day. sat down to have my usual veggie/fruit smoothie when i was overcome my a five minute extreme spinning feeling that made me want to vomit. after i notice my nasal was congested and i was drained. never felt like this before!