I feel I pass out from any type of physical exertion, including very light physical exertion?

I’m a 34 year old male and for the past 1 1/2 years I have felt as if I would pass out from any type of physical exertion including very light physical exertion. I have never had any health problems. I went to a college football game 2 months ago and after climbing 30-40 steps I thought I was going to pass out. I felt like I was going to vomit. I was so hot. I removed my shoes and socks and hat and poured a bottle of cold water on my head and just laid on the seats. Very embarrassing but after about 10 minutes I felt fine. Another example was last Christmas I was carrying a box of canned food up some stairs then down the hallway. Half way there I couldn’t go any farther. I put the box down. I sat in the break room and tried to cool down by sipping on a cup of water while I was hyperventilating then I ran to the bathroom vomited and put my head in the sink and ran cold water on my head. There are many more examples. While it is happening I feel like I can’t breathe well, I feel like it is 2000 degrees, I feel light headed as if I am going to pass out, I feel nauseous. Also during sex I get these symptoms. I’m a non-smoker. My weight has gone up to 220 lbs from 160 over the past 7 years. I thought that could be a possible cause. I’m not sure if this would be heart, lungs, or something else. I do plan on going to the doctor about this but I wanted to get some advice first. Any ideas on what could be the cause? Also when I do go to the doctor should I go to my family doctor or should I see a specialist?