"I then felt dizzy, sick, hot, shaky, breathless"
I think this alone sums it up for me. If you were having something as severe as you suspect, these would be present with you constantly. You're talking about a blockage in the blood vessels of your lungs. Something incredibly serious. Some, small ones, can cause no symptoms, but those are not worth worrying about - they can clear up by themselves. For it to be serious, you would be majorly ill.
The passage of symptoms you are describing seems to follow something like this, if I'm reading right.
1. You have a fear of PE, which is quite a common fear.
2. You had some muscle tightness in your calf, which scared you more. You saw a doctor and it went away. Nothing to be scared of :)
3. You had breathlessness when climbing the stairs. A scary symptom, I admit, but so common and potentially caused by any number of harmless things.
4. You googled. After googling, you then went into a full blown panic, which makes it all seem worse. This is nothing abnormal when suffering from HA.
This is typical of anxiety, and very, very commonly seen around these boards. You've developed a fear of something, and you're equating every symptom you have to it. It's hard, I know, but you have to accept a simple fact: If you had a severe PE, you wouldn't be discussing it on these boards. You would be desperately ill, possibly even unconscious. It isn't a little bit of chest tightness and breathlessness on exertion, it's a serious medical emergency. You're not having one :)