Thanks for your question on Healthcare Magic. I can understand your concern. Yes, these symptoms are more suggestive of heat stroke. Palpitations, giddiness, perspiration, chest heaviness, black outs etc are symptoms of heat stroke especially when history of prolonged sun exposure is there. So in your case due to prolonged sun exposure, you might have developed heat stroke. Your symptoms are improving after drinking plenty of water. This is another indication of heat stroke. So better to avoid direct sun exposure and use umbrella. Hope I have solved your query. I will be happy to help you further. Wish you good health. Thanks.