hi, sounds like some health anxiety going on. panic & anxiety forum has good stuff to help.
in the meantime, you are clear, sounds more like a panic episode. distraction is key. do not dr. google, you will dx yourself with the plague!!!
it is common to feel worried, espec ially when ya been sick with other stuff, but this just sounds like some anxiety, and this is a common thing as they are like heart probs, but are not. when my thinking goes awry i stick me head under the cold shower for 30 seconds, the cold shocks us back, and helps the synapses, this is scientific, esp with cold water therapy. ice in the hands too is a good one. keep well.