<s>[INST] I fainted the other day after riding a bike about 2miles in 95˚ heat. I was standing in line at a deli and felt faint, so I sat down, I felt dizzy and my vision was fading to black. I drank some water. But when I got up again, I fainted. I had not eating breakfast. I had only drank a few ounces of water in 12 hours prior to fainting. I am 44. Very lean. Recently lost about 10 pounds due to a change diet.I was taken to an ER. The ran several tests. EKG (OK) xrays (OK). Blood was ok. I think I smacked my head pretty good. I feel a bit woozy or slow sometimes.The doctor said my triponum level was indeterminate. It was .1  they tested it again several hours later and it was the same. He said it was not high but it was not low.THey are suggesting more tests. What do you think? [/INST] Hello!Welcome on Healthcaremagic!The fainting episodes seem to be related to dehydration or an electrolyte imbalance. There is nothing to worry about!Anyway, I agree with your doctor on the decision on performing further tests, just to be sure that everything is OK. For this reason, I would recommend performing a brain MRI (as you smacked your head), an EEG for possible seizures and an ECG Holter monitoring (to exclude possible cardiac arrhythmia). Hope you will find this answer helpful!Best wishes, Dr. Aida </s>