Dizziness, Nausea, Sweating, Urge To Pass Stool After Exercise. Reason?

I am an active relatively healthy 77 year old woman; recently retired who works out every day ( aerobics and strength training with free weights). Yesterday, after completing a set of upper body exercises lying prone on a work out bench, I rose to a seated position and immediately became dizzy, nauseated, sweaty, faint and felt as if I needed to have a bowel movement . The symptoms decreased in severity after about 3 -4 minutes but still persisted in a milder form. After returning home (just an elevator’s ride up to my apartment) I had some water and then fell asleep. After a short nap I felt better but weak. I went to bed for the night quite early and slept for about 10 hours, rising to go to the bathroom twice during the night (without dizziness ). I still feel weak.