Heat exhaustion or new type of migraine?

Hi! I am new to this forum/site and glad I found it! I am a 62 year old female who has suffered migraines/aura with and without headache from time to time since my 30's. Yesterday afternoon, I was at the community outdoor pool for 3 hours. I was frequently cooling off in the pool, but was in the sun and I admit, did not drink any water, etc. while there. I was feeling fine, but turned my head to look at some swimmers, and experienced a weird, dizzy sensation. After a moment, I began to feel dizzy in general and realized I needed to get out of the sun. As I walked across the cement, I felt drunk! Could not walk a straight line. Made it to the shade, sat a few minutes and walked into the bathroom and drank some water.

Fortunately I live close to the pool and managed to drive home ok. Thinking this was surely heat exhaustion, although I did not have all of the symptoms, I lay down in front of a fan, and began to sip cool water. However, the vertigo did not disappear and I quickly became nauseous and vomited. I lay on the cool bathroom floor and felt a little better. Eventually got up and got back in bed, but was still nauseous and then began to get chills like I was freezing and had to put on a blanket. This went on for about an hour until I finally fell asleep exhausted! I woke after a couple of hours.....nausea and vertigo gone, but head ached and felt exhausted. Then slept the rest of the night, but woke up with headache and still no energy. Today feeling a bit better, but still tired and mild headache. So now wondering was it heat exhaustion, a virus or am I developing vestibular migraine now in addition to my normal migraines???? Any ideas?