Sounds like diabetes, at least the hypoglysemic part of it.
Headache, heart pallipitations, irratiblity are all signs. on the other hand it also sounds like a cardio issue.
I have diabetes and partially blocked caroted arterys too.
This is serious, you could have a stroke if you let this go.
I did, and did have a stroke in Feb, thank god it was a light one, but it still did damage.
I don't suffer from heart problems, all arteries are clear except the ones in my neck leading to my brain, lack of oxygen will cause the sympthoms you described.
Take it from someone who has been there, don't play with this stuff, it can kill you!
Get to a Dr. ASAP, not a week from now or you may be too late.