Email spamming from my email account

It appears that my email has either been cloned or they are somehow sending emails through my account. All of my contacts have been hit and it seems to be happening on a weekly basis now.
They all say basically the same thing. “did you see this posted last week? It’s pretty cool.” This is followed by an obsure link.
Does anyone know how I can find out how it is being done and is there anyway to stop it?
I have had the same email address for 8 years now so it would be really hard to change addresses.

Change your password.

And use two part authentication.

I will give that a try.

Yep what Frank said.