How soon after eating can I lay down? If I lay down to soon my food comes right back up.

Sounds like you have GERD or gastroesophageal reflux. Wait about 1/2 hour before trying to lay down. When you do lay down, try and keep your head elevated some. If this continues, you may want to make an appointment with your doctor.

There's no set time to wait after eating before you can lay down, but some people do suffer from conditions that make this a little uncomfortable for a while after eating.

I'd wait for at least an hour before lying down if you're struggling to keep food down when doing so.  Having said that, I'd also recommend that you seek the advice of a doctor, who will be able to check whether there's any kind of illness present that's causing these symptoms. 

What could cause food to come back up when laying down?

As mentioned in an earlier response, the symptom of being unable to keep food down could relate to gastroesophageal reflux, which is the return of your stomach's contents to your esophagus.

Laying down quickly after eating may exacerbate the symptoms of gastroesophageal, so it's best to avoid doing this immediately after eating.

Other symptoms of gastroesophageal reflux

Alongside the stomach's contents travelling back to the esophagus, people suffering from gastroesophageal reflux may also experience indigestion and heartburn.