Our almost three year old son has trown up everything he has eaten today... Anything I can do for him at home? Or do I need to take him in?

Try feeding a couple saltines like crackers, they are good for when you're throwing up because they are light on the stomach. If you are comfortable with this one, give him small sips of ginger ale because ginger helps settle the stomach, just very small sips. If he handles both well, just continue it for a few days and try to increase the amount of crackers you give him until he can eat normal again.

If there is a fever I would try to bring that down by a cooling bath/meds before giving him any more food and then think about sips of a rehydrating beverage/sport beverage/pedialite, etc.

It's never a bad idea to consult a doctor or pharmacist to be sure.

Very true, that is those were the only things I could think of. Hope your son feels better though.

Does he have a fever? At the age of 3 fevers can go from low to extremely high very quickly. There's also a risk of dehydration, and toddlesr can become dehydrated fast.

If his temperature goes above 102, rush him to the doctor or hospital. Give him pedialyte to help with the dehydration.

Consulting with your doctor is never a bad idea, especially with a child this young.