Please tell me, what could this be. Today I ate porridge for lunch, th…

Please tell me, what could this be. Today I ate porridge for lunch, then I suddenly felt short of breath and started to feel nauseous; at one point while standing my vision blurred. It's 33°C outside. I have a heaviness in my stomach. I ate kefir and prunes and felt a bit better, but then the nausea and shortness of breath returned. I don't have swelling, but my legs get tired, I'm gaining weight normally. By the evening my temperature rose, but I was no longer nauseous. Could this be gestosis (preeclampsia)? Or is it really just the heat affecting me like this?