Images won't link to what I tell them to

Hi,

For the past couple of days I’ll be making a post with a product. I have the title, the featured image, and another image in these posts that all link to the same page (amazon)

Now I just started adding more posts, and although I haven’t changed anything and my images are SUPPOSED to link to what I put them to link to, they link to http://www.mydomain.com/www.thelinkiwant.com

For some reason my domain keeps popping up in front of the link that I input, yet when I click on the image to edit the link my domain name doesn’t show up.

What’s wrong?