I have a 2 year old boy that is rapidly loosing weight. A LOT! Rib cage shows. He is dewormed regularly and eats all of his food. Recently he started to regurgitate his food and eat it again, this stopped as I mix his food with water and has not happened since but the weight is still dropping. Any ideas??????? TIA

And what does his stool look like? That will tell you more in a nutshell than the info you provided. Could be anything, but without more info , who could say ? Maybe Giardia , maybe something more serious, take stool with you to Vet . You said he is wormed regularly, wormed for what , using what product ??

I agree. Get the boy to the vet asap. Massive weight loss could be many things.

Regurgitation of food and weight loss could be a megaesophagus (an anotomical defect of the esophagus) or a malabsorbtion disorder, where he is unable to assimilate nutrients. Or an obstruction.
Could he be vomiting up his food outside and you're not seeing it? Is he hungry all the time? Vomiting or regurgitating (regurgitation does not involve abdominal muscle contraction, food just comes back up)? Any diarrhea or inappetance? What are you worming him with? Some over the counter wormers cause more damage than good, and do not need to be repeated at his age.
I agree, this guy needs some veterinary care. It could be anything, and does not sound like an easy home fix. Good luck and let us know what the veterinarian says?

If after a good thorough veterinary examination/ultrasound/xrays you still find nothing, you may want to try: switching to a no corn food and adding probiotics - this worked for us in a very similar situation, in our case our vet could not find the cause.

All the best to you and your boy.