Welcome to Connect, @jwoj. I want to assure you that you are not being "paranoid"– naturally, you have a lot of questions (without answers) and you aren't sure about what lies ahead.
You may also notice that I moved your post to this existing discussion about heart stiffness, as I thought it would be beneficial for you to be introduced to the many members who have discussed much of what you are experiencing.
When you click VIEW & REPLY in your email notification, you will see the whole discussion and can join in, meet, and participate with other members.

Stiff heart or diastolic dysfunction means that your heart (ventricles) is having trouble relaxing between beats which limits the amount of blood the ventricles can collect for the next heartbeat, and the heart has to work harder. This can happen when the heart muscle is overworked and "bulks up" (just like arm muscles would if you lifted weights), or the heart muscle becomes less flexible – a normal physiologic change with age. https://www.healio.com/cardiology/learn-the-heart/cardiology-review/topic-reviews/diastolic-dysfunction

Here are two published studies about the role of echocardiography in the evaluation of athletes, which I hope will provide some answers:
– https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4516021/
– https://onlinelibrary.wiley.com/doi/full/10.1002/cce2.65

@jwoj, what concerns you most about the echo findings?