It would be great if you can be monitored during a ride! Then - if everything is checking out to be fine - maybe the chest pain/ heart feeling "tired" are results of your effort that will fade as your body adjusts to the new demands you are putting on it. I think it's really wonderful that you're taking care of your health and keeping on with the cycling.

I hope soon that you'll find a riding buddy or two. Keep an ear out for what clubs might be around that do beginner rides.

Keep in touch and let us know how it's going.