What Causes Vertigo, Nausea, Dry Heaves And Dizziness?

Last couple of allergy seasons, I ve felt a bit of vertigo after walking my dog, usually early a.m. or evening... but just the first couple of weeks of the season. The vertigo is light, and subsides in a couple of hours. Taking an antihistamine seemed to help. Haven t had it at all this season. This a.m., I awoke with a very strong feeling of vertigo, and it lasted about 4 hours... until it made me nauseous, and when I went into the bathroom to vomit, it was more like a dry heave... but then the dizziness began to dissipate. Still feel a little odd, more of remnant of this a.m. I have also had a bit of a stiff neck of late, left side... both from the deltoid in, and from the pectoral collarbone area up to the neck. A friend mentioned that dizziness which ends through some sort of exertion (dry heave) could be from an abnormal heart beat... or from restricted blood flow through the carotid. Of course, it has me concerned. I ve always had great EKGs, had a heart CAT scan 10 years ago (part of a story I was doing), with a perfect result. My last checkup showed overall cholesterol was 152. So I want to go see a physician, but thought I d check here as well.