So my heart has been beating and racing pretty fast today and I don't have a clue as to why that might be. It sort of hurts a little bit. Could it be because lack of sleep or what?

There are hundreds of causes of this. You will have to see a doctor as it would not only foolish, but dangerous, for someone online to give you medical advice regarding cardiac issues.

I am 100% behind J_9 on this... you really NEED to see a doctor about this... specifically a cardiologist to find ot why. I have a family member who has experienced this for years.

Smoothy what did they have?

It doesn't matter what Smoothy's family member had. That is totally unrelated to you.

Yes, as J_9 states, you'll have to be seen and diagnosed by a doctor... there is more than one thing that causes it... some can be treated and others can't. THere really isn't a one size fits all answer to this problem. It might be as simple as treatment to deal with panic attacks.. to as bad as needing a pacemaker to regulate it... and there are a LOT of possibilities between those two extremes.

My family member has a problem that leans towards the latter... and has been monitored for years in case it gets worse, in which case intervention would be needed. But only a physician can determine the root cause of yours.