What is wrong with my dog?

Question
My dog has been acting strangely lately. He has been puking up a clear but kind of foamy liquid. He has been very weak and hasn't really been getting up to walk. Could you possibly point me in the right way of what this might be?

Answer
Robin-

Vomiting, lethergy and weakness are very serious symptoms. Please take your dog to the vet ASAP. I am unable to diagnose over the internet, it could be thousands of different illnesses depending on age of your dog, how long this has been going on, other symptoms, recent diet.. etc. Please take your dog to the vet immediatly. If he is to the point where he can not walk, whatever he does have could be fatal.

I hope he feels better soon!